Preparation and utility of substituted imidazopyridine compounds with hypnotic effects

ABSTRACT

The present disclosure is directed to modulators of GABA A  receptors and pharmaceutically acceptable salts and prodrugs thereof, the chemical synthesis thereof, and the medical use of such compounds for the treatment and/or management of sleep disorders and/or for providing a patient in need with a hypnotic, anxiolytic or anti-convulsive effect are described.

RELATED APPLICATIONS

This patent application claims the benefit of U.S. Provisional PatentApplication No. 60/810,935 filed Jun. 5, 2006, and is incorporated byreference in its entirety.

FIELD

The present disclosure is directed to modulators of GABA_(A) receptorsand pharmaceutically acceptable salts and prodrugs thereof, the chemicalsynthesis thereof, and the medical use of such compounds for thetreatment and/or management of sleep disorders and/or for providing apatient in need with a hypnotic, anxiolytic or anti-convulsive effect.

BACKGROUND

Zolpidem (Ambien®) is a therapeutic agent thought to interact with thebenzodiazepine receptor within the GABA_(A) receptor complex. As such,zolpidem shares much of its pharmacology with the benzodiazepines.Zolpidem, however, is more selective, interacting primarily with the ω₁receptor, which explains the lesser degree of myorelaxant andanticonvulsant effects observed in animal studies, relative to thebenzodiazepines. Eszopiclone (Lunesta®, Sepracor), indiplon (Pfizer),gaboxadol (Merck), and zaleplon (Sonata®, King) are also importantmembers of this class of purported GABA_(A) modulators.

Ambien® is converted in vivo by oxidative and conjugative degradation tomultiple metabolites. The major metabolites include phase I metabolismleading to demethylation at the nitrogen center and benzylic andimidazopyridyl hydroxylation, as well as significant phase II metabolismincluding glucuronidation of the hydroxylated metabolites. Zolpidem ismetabolized in part by polymorphically expressed isozymes of cytochromeP₄₅₀, including CYP2C9. The activity of zolpidem is cut short primarilyby oxidation of the benzylic methyl group. The oxidation of this groupaccounts for approximately 84% of the net intrinsic clearance. Theimidazopyridyl methyl group oxidation accounts for approximately another12% of net intrinsic clearance. As such, zolpidem does not provideadequate duration of action for many patients. Consequently, itsapplication in polypharmacy is necessarily complex, has potential foradverse events, and increases inter-patient variability in response topolypharmacy.

There is therefore a need for hypnotic agents which can provide adequateduration of action to patients in need.

SUMMARY OF THE INVENTION

Described herein are deuterated modulators of GABA_(A) receptors. In oneembodiment, the deuterium enrichment occurs at a specific position onthe modulator. In another embodiment, the deuterium enrichment is noless than about 1%. In a further embodiment, the deuterium enrichment isno less than about 10%. In yet a further embodiment, the deuteriumenrichment is no less than about 20%. In one embodiment, the deuteriumenrichment is no less than about 50%. In a further embodiment, thedeuterium enrichment is no less than about 70%. In a further embodiment,the deuterium enrichment is no less than about 80%. In yet a furtherembodiment, the deuterium enrichment is no less than about 90%. In afurther embodiment, the deuterium enrichment is no less than about 95%.In one embodiment, the deuterated modulator has a slower rate ofmetabolism than the corresponding protiated inhibitor.

Further described herein are deuterated analogs of zolpidem,eszopiclone, indiplon, gaboxadol, and zaleplon, including, for each ofthe aforementioned compounds, a single enantiomer, a mixture of a(+)-enantiomer and a (−)-enantiomer, a mixture of about 90% or more byweight of the (−)-enantiomer and about 10% or less by weight of the(+)-enantiomer, a mixture of about 90% or more by weight of the(+)-enantiomer and about 10% or less by weight of the (−)-enantiomer, anindividual diastereomer, or a mixture of diastereomers thereof; or apharmaceutically acceptable salt, solvate, or prodrug. In oneembodiment, the deuterium enrichment occurs at a specific position onthe analog. In another embodiment, the deuterium enrichment is no lessthan about 1%. In a further embodiment, the deuterium enrichment is noless than about 10%. In yet a further embodiment, the deuteriumenrichment is no less than about 20%. In another embodiment, thedeuterium enrichment is no less than about 50%. In yet anotherembodiment, the deuterium enrichment is no less than about 70%. In afurther embodiment, the deuterium enrichment is no less than about 80%.In yet a further embodiment, the deuterium enrichment is no less thanabout 90%. In a further embodiment, the deuterium enrichment is no lessthan about 95%. In one embodiment, the deuterated compound has a slowerrate of metabolism than the corresponding protiated compound.

Provided herein are compounds of Formula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that compounds of Formula 1 contain at least one deuteriumatom; and provided that deuterium enrichment in compounds of Formula 1is at least about 1%.

In one embodiment is a compound selected from the group consisting of:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof.

In one embodiment, the deuterium enrichment is no less than about 1%. Ina further embodiment, the deuterium enrichment is no less than about10%. In a further embodiment, the deuterium enrichment is no less thanabout 20%. In a further embodiment, the deuterium enrichment is no lessthan about 50%. In a further embodiment, the deuterium enrichment is noless than about 70%. In a further embodiment, the deuterium enrichmentis no less than about 80%. In a further embodiment, the deuteriumenrichment is no less than about 90%. In a further embodiment, thedeuterium enrichment is no less than about 95%. In one embodiment, thedeuterated compound has a slower rate of metabolism than thecorresponding protiated compound.

Also provided herein is a method of treating a mammal suffering from adisease or condition involving a benzodiazepine receptor, comprisingadministering to the mammal a therapeutically effective amount of acompound of Formula 1

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that the compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in the compound of Formula 1 is atleast about 1%;

so as to affect decreased inter-individual variation in plasma levels ofthe compound or a metabolite thereof as compared to the non-isotopicallyenriched compound.

In one aspect is a method of treating a mammal suffering from a diseaseor condition involving a benzodiazepine receptor, comprisingadministering to the mammal a therapeutically effective amount of acompound of Formula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%;

so as to affect increased average plasma levels of said compound perdosage unit thereof as compared to the non-isotopically enrichedcompound.

In one embodiment is a method wherein the disease or condition isselected from the group consisting of a sleep disorder and a disease inwhich a hypnotic, an anxiolytic or an anti-convulsive effect isbeneficial.

In one aspect is a method of treating a mammal suffering from a diseaseor condition involving a benzodiazepine receptor, comprisingadministering a therapeutically effective amount of a compound ofFormula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%;

so as to affect decreased average plasma levels of at least onemetabolite of the compound per dosage unit thereof as compared to thenon-isotopically enriched compound.

In another aspect is a method of treating a mammal suffering from adisease or condition involving a benzodiazepine receptor, comprisingadministering a therapeutically effective amount of a compound ofFormula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%;

so as to affect a decreased metabolism by at least onepolymorphically-expressed cytochrome P₄₅₀ isoform in mammalian subjectsper dosage unit thereof as compared to the non-isotopically enrichedcompound.

In one aspect is a method of treating a mammal suffering from a diseaseor condition involving a benzodiazepine receptor, comprisingadministering a therapeutically effective amount of a compound ofFormula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%;

so as to affect a decreased inhibition of at least one cytochrome P₄₅₀isoform in mammalian subjects per dosage unit thereof as compared to thenon-isotopically enriched compound.

In one embodiment is a method wherein the cytochrome P₄₅₀ isoform isselected from the group consisting of CYP1A1, CYP1A2, CYP1B1, CYP2A6,CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1,CYP2G1, CYP2J2, CYP2R1, CYP2S1, CYP3A4, CYP3A5, CYP3A5P1, CYP3A5P2,CYP3A7, CYP4A11, CYP4B1, CYP4F2, CYP4F3, CYP4F8, CYP4 μl, CYP4F12,CYP4X1, CYP4Z1, CYP5A1, CYP7A1, CYP7B1, CYP8A1, CYP8B1, CYP11A1,CYP11B1, CYP11B2, CYP17, CYP19, CYP21, CYP24, CYP26A1, CYP26B1, CYP27A1,CYP27B1, CYP39, CYP46, and CYP51,

In one embodiment is a method wherein the cytochrome P₄₅₀ isoform isselected from the group consisting of CYP2C8, CYP2C9, CYP2C19, andCYP2D6.

In another aspect is a method of treating a mammal suffering from adisease or condition involving a benzodiazepine receptor, comprisingadministering a therapeutically effective amount of a compound ofFormula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%;

so as to elicit an improved clinical effect during the treatment in saidmammal per dosage unit thereof as compared to the non-isotopicallyenriched compound.

Also disclosed herein are pharmaceutical compositions comprising atherapeutically effective amount of a compound of Formula 1, or the(−)-enantiomer of a compound of Formula 1, or the (+)-enantiomer of acompound of Formula 1, or a pharmaceutically acceptable salt, solvate,or prodrug thereof, and a pharmaceutically acceptable excipient orcarrier.

In one embodiment the pharmaceutical composition is a suitable oral,parenteral, or intravenous infusion administration. In anotherembodiment is a pharmaceutical composition wherein oral administrationcomprises administering a tablet or a capsule. In another embodiment isa pharmaceutical composition wherein a compound of Formula 1 isadministered in a dose of about 0.1 milligram to about 100 milligramtotal daily.

Further, disclosed herein are methods of treating a mammal sufferingfrom a disease or condition involving a benzodiazepine receptor,comprising administering to the mammal a therapeutically effectiveamount of a compound of Formula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof, or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%.

In addition, disclosed herein are methods of treating a mammaliansubject having, suspected of having, or being prone to a disease orcondition, such as a disease or condition selected from the groupconsisting of a sleep disorder and/or a disease in which a hypnotic, ananxiolytic or an anti-convulsive effect is beneficial.

Also provided herein are articles of manufacture and kits containingcompounds described herein. By way of example only a kit or article ofmanufacture can include a container (such as a bottle) with a desiredamount of a compound (or pharmaceutical composition of a compound)described herein. Such a kit or article of manufacture can furtherinclude instructions for using the compound (or pharmaceuticalcomposition of a compound) described herein. The instructions can beattached to the container, or can be included in a package (such as abox or a plastic or foil bag) holding the container.

In another aspect is the use of a compound described herein in themanufacture of a medicament for treating a disease or condition in ananimal in which a benzodiazapine receptor contributes to the pathologyand/or symptomology of the disease or condition. In a further oralternative embodiment, said disease or condition is non-specific pain,tension-type pain, headache, migraine, lower back pain, sciatica, dentalpain, muscular pain, pain associated with acute soft tissue injuries,bursitis, tendonitis, lumbago, periarthritis, tennis elbow, sprains,strains, muscular problems associated with sports injuries, muscularproblems associated with accidents, period pain, primary dysmenorrhoea,acute sore throat pain, osteoartlritis, rheumatoid arthritis, cancer,any disorder requiring analgesic response, any disorder requiringanti-inflammatory response, any disorder requiring antipyretic response,any conditions mediated by cyclooxygenase, cystic fibrosis, dementia,Alzheimer's disease, and may be used as an anesthetic, analgesic,entheogen, therapeutic cataleptic, and neuroprotectant.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

DETAILED DESCRIPTION

To facilitate understanding of the disclosure set forth herein, a numberof terms are defined below.

As used herein, the singular forms “a,” “an,” and “the” may refer toplural articles unless specifically stated otherwise. Generally, thenomenclature used herein and the laboratory procedures in organicchemistry, medicinal chemistry, and pharmacology described herein arethose well known and commonly employed in the art. Unless definedotherwise, all technical and scientific terms used herein generally havethe same meaning as commonly understood by one of ordinary skill in theart to which this disclosure belongs. In the event that there is aplurality of definitions for a term herein, those in this sectionprevail unless stated otherwise.

The term “subject” refers to an animal, including, but not limited to, aprimate (e.g., human), cow, sheep, goat, horse, dog, cat, rabbit, rat,or mouse. The terms “subject” and “patient” are used interchangeablyherein in reference, for example, to a mammalian subject, such as ahuman subject.

The terms “treat,” “treating,” and “treatment” are meant to includealleviating or abrogating a disorder, disease, or condition; or one ormore of the symptoms associated with the disorder, disease, orcondition; or alleviating or eradicating the cause(s) of the disorder,disease, or condition itself.

The terms “prevent,” “preventing,” and “prevention” refer to a method ofdelaying or precluding the onset of a disorder, disease, or condition;and/or its attendant symptoms, barring a subject from acquiring adisease or reducing a subject's risk of acquiring a disorder, disease,or condition.

The term “therapeutically effective amount” refers to the amount of acompound that, when administered, is sufficient to prevent developmentof, or alleviate to some extent, one or more of the symptoms of thedisorder, disease, or condition being treated. The term “therapeuticallyeffective amount” also refers to the amount of a compound that issufficient to elicit the biological or medical response of a cell,tissue, system, animal, or human that is being sought by a researcher,veterinarian, medical doctor, or clinician.

The term “pharmaceutically acceptable carrier,” “pharmaceuticallyacceptable excipient,” “physiologically acceptable carrier,” or“physiologically acceptable excipient” refers to apharmaceutically-acceptable material, composition, or vehicle, such as aliquid or solid filler, diluent, excipient, solvent, or encapsulatingmaterial. Each component must be “pharmaceutically acceptable” in thesense of being compatible with the other ingredients of a pharmaceuticalformulation. It must also be suitable for use in contact with the tissueor organ of humans and animals without excessive toxicity, irritation,allergic response, immunogenicity, or other problems or complications,commensurate with a reasonable benefit/risk ratio. See, Remington: TheScience and Practice of Pharmacy, 21st Edition; Lippincott Williams &Wilkins: Philadelphia, Pa., 2005; Handbook of Pharmaceutical Excipients,5th Edition; Rowe et al., Eds., The Pharmaceutical Press and theAmerican Pharmaceutical Association: 2005; and Handbook ofPharmaceutical Additives, 3rd Edition; Ash and Ash Eds., GowerPublishing Company: 2007; Pharmaceutical Preformulation and Formulation,Gibson Ed., CRC Press LLC: Boca Raton, Fla., 2004).

The term “pharmaceutical composition” refers to a mixture of a compounddisclosed herein with other chemical components, such as diluents orcarriers. The pharmaceutical composition facilitates administration ofthe compound to an organism. Multiple techniques of administering acompound exist in the art including, but not limited to, oral,injection, aerosol, parenteral, and topical administration.Pharmaceutical compositions can also be obtained by reacting compoundswith inorganic or organic acids such as hydrochloric acid, hydrobromicacid, sulfuric acid, nitric acid, phosphoric acid, methanesulfonic acid,ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid and thelike.

The term “carrier” defines a chemical compound that facilitates theincorporation of a compound into cells or tissues. For example dimethylsulfoxide (DMSO) is a commonly utilized carrier as it facilitates theuptake of many organic compounds into the cells or tissues of anorganism.

The term “deuterium enrichment” refers to the percentage ofincorporation of deuterium at a given position in a molecule in theplace of hydrogen. For example, deuterium enrichment of about 1% at agiven position means that about 1% of molecules in a given samplecontain deuterium at the specified position. Because the naturallyoccurring distribution of deuterium is about 0.0156%, deuteriumenrichment at any positions in a compound synthesized using non-enrichedstarting materials is about 0.0156%. The deuterium enrichment can bedetermined using conventional analytical methods known to one ofordinary skill in the art, including mass spectrometry and nuclearmagnetic resonance spectroscopy.

The term “isotopic enrichment” refers to the percentage of incorporationof a less prevalent isotope of an element at a given position in amolecule in the place of the more prevalent isotope of the element.

The term “non-isotopically enriched” refers to a molecule in which thepercentages of the various isotopes are substantially the same as thenaturally occurring percentages.

The terms “substantially pure” and “substantially homogeneous” meansufficiently homogeneous to appear free of readily detectable impuritiesas determined by standard analytical methods used by one of ordinaryskill in the art, including, but not limited to, thin layerchromatography (TLC), gel electrophoresis, high performance liquidchromatography (HPLC), nuclear magnetic resonance (NMR), and massspectrometry (MS); or sufficiently pure such that further purificationwould not detectably alter the physical and chemical properties, orbiological and pharmacological properties, such as enzymatic andbiological activities, of the substance. In certain embodiments,“substantially pure” or “substantially homogeneous” refers to acollection of molecules, wherein at least about 50%, at least about 70%,at least about 80%, at least about 90%, at least about 95%, at leastabout 98%, at least about 99%, or at least about 99.5% of the moleculesare a single compound, including a racemic mixture or singlestereoisomer thereof, as determined by standard analytical methods

The term “about” or “approximately” means an acceptable error for aparticular value as determined by one of ordinary skill in the art,which depends in part on how the value is measured or determined. Incertain embodiments, “about” can mean with 1 or more standarddeviations.

The terms “active ingredient” and “active substance” refer to acompound, which is administered, alone or in combination with one ormore pharmaceutically acceptable excipients, to a subject for treating,preventing, or ameliorating one or more symptoms of a disorder ordisease.

The terms “drug,” “therapeutic agent,” and “chemotherapeutic agent”refer to a compound, or a pharmaceutical composition thereof, which isadministered to a subject for treating, preventing, or ameliorating oneor more symptoms of a disorder or disease.

The term “release controlling excipient” refers to an excipient whoseprimary function is to modify the duration or place of release of theactive substance from a dosage form as compared with a conventionalimmediate release dosage form.

The term “non-release controlling excipient” refers to an excipientwhose primary function do not include modifying the duration or place ofrelease of the active substance from a dosage form as compared with aconventional immediate release dosage form.

The term “halogen”, “halide” or “halo” includes fluorine, chlorine,bromine, and iodine.

The terms “alkyl” and “substituted alkyl” are interchangeable andinclude substituted, optionally substituted and unsubstituted C₁-C₁₀straight chain saturated aliphatic hydrocarbon groups, substituted,optionally substituted and unsubstituted C₂-C₁₀ straight chainunsaturated aliphatic hydrocarbon groups, substituted, optionallysubstituted and unsubstituted C₂-C₁₀ branched saturated aliphatichydrocarbon groups, substituted and unsubstituted C₂-C₁₀ branchedunsaturated aliphatic hydrocarbon groups, substituted, optionallysubstituted and unsubstituted C₃-C₈ cyclic saturated aliphatichydrocarbon groups, substituted, optionally substituted andunsubstituted C₅-C₈ cyclic unsaturated aliphatic hydrocarbon groupshaving the specified number of carbon atoms. For example, the definitionof “alkyl” shall include but is not limited to: methyl (Me),trideuteromethyl (—CD₃), ethyl (Et), propyl (Pr), butyl (Bu), pentyl,hexyl, heptyl, octyl, nonyl, decyl, undecyl, ethenyl, propenyl, butenyl,penentyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl,isopropyl (i-Pr), isobutyl (i-Bu), tert-butyl (t-Bu), sec-butyl (s-Bu),isopentyl, neopentyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, cyclopentenyl, cyclohexenyl, cycloheptenyl,cyclooctenyl, methylcyclopropyl, ethylcyclohexenyl, butenylcyclopentyl,adamantyl, norbornyl and the like. Alkyl substituents are independentlyselected from the group consisting of hydrogen, deuterium, halogen, —OH,—SH, —NH₂, —CN, —NO₂, ═O, ═CH₂, trihalomethyl, carbamoyl,arylC₀₋₁₀alkyl, heteroarylC₀₋₁₀alkyl, C₁₋₁₀alkyloxy, arylC₀₋₁₀alkyloxy,C₁₋₁₀alkylthio, arylC₀₋₁₀alkylthio, C₁₋₁₀alkylamino,arylC₀₋₁₀alkylamino, N-aryl-N—C₀₋₁₀alkylamino, C₁₋₁₀alkylcarbonyl,arylC₀₋₁₀alkylcarbonyl, C₁₋₁₀alkylcarboxy, arylC₀₋₁₀alkylcarboxy,C₀₋₁₀alkylcarbonylamino, arylC₀₋₁₀alkylcarbonylamino, tetrahydrofuryl,morpholinyl, piperazinyl, hydroxypyronyl, —C₀₋₁₀alkylCOOR₃₀ and—C₀₋₁₀alkylCONR₃₁R₃₂ wherein R₃₀, R₃₁ and R₃₂ are independently selectedfrom the group consisting of hydrogen, deuterium, alkyl, aryl, or R₃₂and R₃₃ are taken together with the nitrogen to which they are attachedforming a saturated cyclic or unsaturated cyclic system containing 3 to8 carbon atoms with at least one substituent as defined herein.

The term “aryl” represents a substituted or unsubstituted, monocyclic,polycyclic, biaryl aromatic groups covalently attached at any ringposition capable of forming a stable covalent bond, certain preferredpoints of attachment being apparent to those skilled in the art (e.g.,3-phenyl, 4-naphthyl and the like). The aryl substituents areindependently selected from the group consisting of hydrogen, deuterium,halogen, —OH, —SH, —CN, —NO₂, trihalomethyl, hydroxypyronyl, C₁₋₁₀alkyl,arylC₀₋₁₀alkyl, C₀₋₁₀alkyloxyC₀₋₁₀alkyl, arylC₀₋₁₀alkyloxyC₀₋₁₀alkyl,C₀₋₁₀alkylthioC₀₋₁₀alkyl, arylC₀₋₁₀alkylthioC₀₋₁₀alkyl,C₀₋₁₀alkylaminoC₀₋₁₀alkyl, arylC₀₋₁₀alkylaminoC₀₋₁₀alkyl,N-aryl-N—C₀₋₁₀alkylaminoC₀₋₁₀alkyl, C₁₋₁₀alkylcarbonyC₀₋₁₀alkyl,arylC₀₋₁₀alkylcarbonylC₀₋₁₀alkyl, C₁₋₁₀alkylcarboxyC₀₋₁₀alkyl,arylC₀₋₁₀alkylcarboxyC₀₋₁₀alkyl, C₁₋₁₀alkylcarbonylaminoC₀₋₁₀alkyl,arylC₀₋₁₀alkylcarbonylaminoC₀₋₁₀alkyl, —C₀₋₁₀alkylCOOR₃₀, and—C₀₋₁₀alkylCONR₃₁R₃₂ wherein R₃₀, R₃₁ and R₃₂ are independently selectedfrom the group consisting of hydrogen, deuterium, alkyl, aryl or R₃₁ andR₃₂ are taken together with the nitrogen to which they are attachedforming a saturated cyclic or unsaturated cyclic system containing 3 to8 carbon atoms with at least one substituent as defined above.

The definition of “aryl” includes but is not limited to phenyl,pentadeuterophenyl, biphenyl, naphthyl, dihydronaphthyl,tetrahydronaphthyl, indenyl, indanyl, azulenyl, anthryl, phenanthryl,fluorenyl, pyrenyl and the like.

Unless otherwise indicated, when a substituent is deemed to be“optionally substituted,” it is meant that the substituent is a groupthat may be substituted with one or more group(s) individually andindependently selected from the group consisting of hydrogen, deuterium,alkyl, cycloalkyl, aryl, heteroaryl, heterocyclic, hydroxy, alkoxy,aryloxy, mercapto, alkylthio, arylthio, cyano, halo, carbonyl,thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl,C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, O-carboxy,isocyanato, thiocyanato, isothiocyanato, nitro, silyl,trihalomethanesulfonyl, and amino, including mono- and di-substitutedamino groups, and the protected derivatives thereof. The protectinggroups that may form the protective derivatives of the abovesubstituents are known to those of skill in the art examples of whichmay be found in references such as Greene and Wuts, Protective Groups inOrganic Synthesis, 3^(rd) Ed., John Wiley & Sons, New York, N.Y., 1999,which is incorporated by reference herein in its entirety.

The term “prodrug” refers to an agent that is converted into the parentdrug in vivo. Prodrugs are often useful because, in some situations,they may be easier to administer than the parent drug.

In light of the purposes described for the present disclosure, allreferences to “alkyl” and “aryl” groups or any groups ordinarilycontaining C—H bonds may include partially or fully deuterated versionsas required to affect the improvements outlined herein.

Deuterium Kinetic Isotope Effect

In an attempt to eliminate foreign substances, such as therapeuticagents, from its circulation system, the animal body expresses variousenzymes, such as the cytochrome P₄₅₀ enzymes or CYPs, esterases,proteases, reductases, dehydrogenases, and monoamine oxidases, to reactwith and convert these foreign substances to more polar intermediates ormetabolites for renal excretion. Some of the most common metabolicreactions of pharmaceutical compounds involve the oxidation of acarbon-hydrogen (C—H) bond to either a carbon-oxygen (C—O) orcarbon-carbon (C—C) π-bond. The resultant metabolites may be stable orunstable under physiological conditions, and can have substantiallydifferent phammacokinetic, pharmacodynamic, and acute and long-termtoxicity profiles relative to the parent compounds. For most drugs, suchoxidations are generally rapid and ultimately lead to administration ofmultiple or high daily doses.

The relationship between the activation energy and the rate of reactionmay be quantified by the Arrhenius equation, k=Ae^(-Eact/RT), whereE_(act) is the activation energy, T is temperature, R is the molar gasconstant, k is the rate constant for the reaction, and A (the frequencyfactor) is a constant specific to each reaction that depends on theprobability that the molecules will collide with the correctorientation. The Arrhenius equation states that the fraction ofmolecules that have enough energy to overcome an energy barrier, thatis, those with energy at least equal to the activation energy, dependsexponentially on the ratio of the activation energy to thermal energy(RT), the average amount of thermal energy that molecules possess at acertain temperature.

The transition state in a reaction is a short lived state (on the orderof 10⁻¹⁴ sec) along the reaction pathway during which the original bondshave stretched to their limit. By definition, the activation energyE_(act) for a reaction is the energy required to reach the transitionstate of that reaction. Reactions that involve multiple steps willnecessarily have a number of transition states, and in these instances,the activation energy for the reaction is equal to the energy differencebetween the reactants and the most unstable transition state. Once thetransition state is reached, the molecules can either revert, thusreforming the original reactants, or new bonds form giving rise to theproducts. This dichotomy is possible because both pathways, forward andreverse, result in the release of energy. A catalyst facilitates areaction process by lowering the activation energy leading to atransition state. Enzymes are examples of biological catalysts thatreduce the energy necessary to achieve a particular transition state.

A carbon-hydrogen bond is by nature a covalent chemical bond. Such abond forms when two atoms of similar electronegativity share some oftheir valence electrons, thereby creating a force that holds the atomstogether. This force or bond strength can be quantified and is expressedin units of energy, and as such, covalent bonds between various atomscan be classified according to how much energy must be applied to thebond in order to break the bond or separate the two atoms.

The bond strength is directly proportional to the absolute value of theground-state vibrational energy of the bond. This vibrational energy,which is also known as the zero-point vibrational energy, depends on themass of the atoms that form the bond. The absolute value of thezero-point vibrational energy increases as the mass of one or both ofthe atoms making the bond increases. Since deuterium (D) has twice themass of hydrogen (H), it follows that a C-D bond is stronger than thecorresponding C—H bond. Compounds with C-D bonds are frequentlyindefinitely stable in H₂O, and have been widely used for isotopicstudies. If a C—H bond is broken during a rate-determining step in achemical reaction (i.e. the step with the highest transition stateenergy), then substituting a deuterium for that hydrogen will cause adecrease in the reaction rate and the process will slow down. Thisphenomenon is known as the Deuterium Kinetic Isotope Effect (DKIE) andcan range from about 1 (no isotope effect) to very large numbers, suchas 50 or more, meaning that the reaction can be fifty, or more, timesslower when deuterium is substituted for hydrogen. High DKIE values maybe due in part to a phenomenon known as tunneling, which is aconsequence of the uncertainty principle. Tunneling is ascribed to thesmall size of a hydrogen atom, and occurs because transition statesinvolving a proton can sometimes form in the absence of the requiredactivation energy. A deuterium is larger and statistically has a muchlower probability of undergoing this phenomenon. Substitution of tritiumfor hydrogen results in yet a stronger bond than deuterium and givesnumerically larger isotope effects.

Discovered in 1932 by Urey, deuterium (D) is a stable andnon-radioactive isotope of hydrogen. It was the first isotope to beseparated from its element in pure form and has twice the mass ofhydrogen, and makes up about 0.02% of the total mass of hydrogen (inthis usage meaning all hydrogen isotopes) on earth. When two deuteriumatoms bond with one oxygen, deuterium oxide (D₂O or “heavy water”) isformed. D₂O looks and tastes like H₂O, but has different physicalproperties. It boils at 101.41° C. and freezes at 3.79° C. Its heatcapacity, heat of fusion, heat of vaporization, and entropy are allhigher than H₂O. It is more viscous and has different solubilizingproperties than H₂O.

When pure D₂O is given to rodents, it is readily absorbed and reaches anequilibrium level that is usually about eighty percent of theconcentration that is consumed by the animals. The quantity of deuteriumrequired to induce toxicity is extremely high. When 0% to as much as 15%of the body water has been replaced by D₂O, animals are healthy but areunable to gain weight as fast as the control (untreated) group. Whenabout 15% to about 20% of the body water has been replaced with D₂O, theanimals become excitable. When about 20% to about 25% of the body waterhas been replaced with D₂O, the animals are so excitable that they gointo frequent convulsions when stimulated. Skin lesions, ulcers on thepaws and muzzles, and necrosis of the tails appear. The animals alsobecome very aggressive; males becoming almost unmanageable. When about30%, of the body water has been replaced with D₂O, the animals refuse toeat and become comatose. Their body weight drops sharply and theirmetabolic rates drop far below normal, with death occurring at about 30to about 35% replacement with D₂O. The effects are reversible unlessmore than thirty percent of the previous body weight has been lost dueto D₂O, Studies have also shown that the use of D₂O can delay the growthof cancer cells and enhance the cytotoxicity of certain antineoplasticagents.

Tritium (T) is a radioactive isotope of hydrogen, used in research,fusion reactors, neutron generators and radiopharmaceuticals. Mixingtritium with a phosphor provides a continuous light source, a techniquethat is commonly used in wristwatches, compasses, rifle sights and exitsigns. It was discovered by Rutherford, Oliphant and Harteck in 1934,and is produced naturally in the upper atmosphere when cosmic rays reactwith H₂ molecules. Tritium is a hydrogen atom that has 2 neutrons in thenucleus and has an atomic weight close to 3. It occurs naturally in theenvironment in very low concentrations, most commonly found as T₂O, acolorless and odorless liquid. Tritium decays slowly (half-life=12.3years) and emits a low energy beta particle that cannot penetrate theouter layer of human skin. Internal exposure is the main hazardassociated with this isotope, yet it must be ingested in large amountsto pose a significant health risk.

Deuteration of pharmaceuticals to improve pharmacokinetics (PK),pharmacodynamics (PD), and toxicity profiles, has been demonstratedpreviously with some classes of drugs. For example, DKIE was used todecrease the hepatotoxicity of halothane by presumably limiting theproduction of reactive species such as trifluoroacetyl chloride.However, this method may not be applicable to all drug classes. Forexample, deuterium incorporation can lead to metabolic switching whichmay even give rise to an oxidative intermediate with a faster off-ratefrom an activating Phase I enzyme (e.g., cytochrome P₄₅₀ 3A4). Theconcept of metabolic switching asserts that xenogens, when sequesteredby Phase I enzymes, may bind transiently and re-bind in a variety ofconformations prior to the chemical reaction (e.g., oxidation). Thishypothesis is supported by the relatively vast size of binding pocketsin many Phase I enzymes and the promiscuous nature of many metabolicreactions. Metabolic switching can potentially lead to differentproportions of known metabolites as well as altogether new metabolites.This new metabolic profile may impart more or less toxicity. Such havenot been heretofore sufficiently predictable a priori for any drugclass.

Deuterated Zolpidem Derivatives

Certain hypnotic agents are known and are shown herein. Zolpidem(Ambien®) is one such compound. The carbon-hydrogen bonds of zolpidemcontain a naturally occurring distribution of hydrogen isotopes, namely¹H or protium (about 99.9844%), ²H or deuterium (about 0.0156%), and ³Hor tritium (in the range between about 0.5 and 67 tritium atoms per 1018protium atoms). Increased levels of deuterium incorporation produce adetectable Kinetic Isotope Effect (KIE) that could affect thepharmacokinetic, pharmacologic and/or toxicologic parameters of suchhypnotic agents in comparison to compounds having naturally occurringlevels of deuterium.

Aspects of the present disclosure describe an approach to designing andsynthesizing new analogs of these hypnotic agents through chemicalmodifications and derivations of the carbon-hydrogen bonds of themodulators and/or of the chemical precursors used to synthesize thesemodulators.

Zolpidem contains groups such as the N-methyl groups, the benzyl methylgroup, and the imidazopyridyl methyl group known to be sites ofcytochrome P₄₅₀ metabolism. The toxicities and pharmacologies of all 12or more resultant metabolites, however, are not known. Furthermore,because polymorphically expressed CYPs oxidize zolpidem, the preventionof such interactions decreases interpatient variability, decreasesdrug-drug interactions, increases T_(1/2), decreases the necessaryC_(max), and improves several other ADMET parameters. Variousdeuteration patterns can be used to a) reduce or eliminate unwantedmetabolites, b) increase the half-life of the parent drug, c) decreasethe number of doses needed to achieve a desired effect, d) decrease theamount of a dose needed to achieve a desired effect, e) increase theformation of active metabolites, if any are formed, and/or f) decreasethe production of deleterious metabolites in specific tissues and/orcreate a more effective drug and/or a safer drug for polypharmacy,whether the polypharmacy be intentional or not. The deuteration approachhas strong potential to slow the metabolism through the geneticallypolymorphically expressed CYPs.

In one aspect, provided herein is a compound of Formula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃; and

provided that compounds of Formula 1 contain at least one deuterium atomand that deuterium enrichment in compounds of Formula 1 is at leastabout 1%.

In one embodiment is a compound selected from the group consisting of:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof.

In one embodiment is a compound of Formula 1 wherein the deuteriumenrichment is no less than about 1%.

In another embodiment is a compound of Formula 1 wherein the deuteriumenrichment is no less than about 10%.

In yet another embodiment is a compound of Formula 1 wherein thedeuterium enrichment is no less than about 20%.

In one embodiment is a compound of Formula 1 wherein the deuteriumenrichment is no less than about 50%.

In a further embodiment is a compound of Formula 1 wherein the deuteriumenrichment is no less than about 70%.

In yet a further embodiment is a compound of Formula 1 wherein thedeuterium enrichment is no less than about 80%.

In one embodiment is a compound of Formula 1 wherein the deuteriumenrichment is no less than about 90%.

In another embodiment is a compound of Formula 1 wherein the deuteriumenrichment is no less than about 95%.

In certain embodiments, R₁ is hydrogen. In other embodiments, R₃ ishydrogen. In some embodiments, R₄ is hydrogen. In other embodiments, R₅is hydrogen. In yet other embodiments, R₆ is hydrogen. In still otherembodiments, R₈ is hydrogen. In yet other embodiments, R₉ is hydrogen.In yet other embodiments, R₁₀ is hydrogen. In still other embodiments,R₁₁, is hydrogen.

In certain embodiments, R₁ is deuterium. In other embodiments, R₃ isdeuterium. In some embodiments, R₄ is deuterium. In other embodiments,R₅ is deuterium. In yet other embodiments, R₆ is deuterium. In stillother embodiments, R₈ is deuterium. In yet other embodiments, R₉ isdeuterium. In yet other embodiments, R₁₀ is deuterium. In someembodiments, R₁₁ is deuterium.

In certain embodiments, R₁ is not hydrogen. In other embodiments, R₃ isnot hydrogen. In some embodiments, R₄ is not hydrogen. In otherembodiments, R₅ is not hydrogen. In yet other embodiments, R₆ is nothydrogen. In still other embodiments, R₈ is not hydrogen. In yet otherembodiments, R₉ is not hydrogen. In yet other embodiments, R₁₀ is nothydrogen. In still other embodiments, R₁₁ is not hydrogen.

In certain embodiments, R₁ is not deuterium. In other embodiments, R₃ isnot deuterium. In some embodiments, R₄ is not deuterium. In otherembodiments, R₅ is not deuterium. In yet other embodiments, R₆ is notdeuterium. In still other embodiments, R₈ is not deuterium. In yet otherembodiments, R₉ is not deuterium. In yet other embodiments, R₁₀ is notdeuterium. In still other embodiments, R₁₁ is not deuterium.

In further embodiments, R₂ is —CH₃. In other embodiments, R₇ is —CH₃, insome embodiments, R₁₂ is —CH₃. In yet other embodiments, R₁₃ is —CH₃.

In further embodiments, R₂ is —CDH₂. In other embodiments, R₇ is —CDH₂,in some embodiments, R₁₂ is —CDH₂. In yet other embodiments, R₁₃ is—CDH₂.

In further embodiments, R₂ is —CD₂H. In other embodiments, R₇ is —CD₂H,in some embodiments, R₁₂ is —CD₂H. In yet other embodiments, R₁₃ is—CD₂H.

In further embodiments, R₂ is —CD₃. In other embodiments, R₇ is —CD₃, insome embodiments, R₁₂ is —CD₃. In yet other embodiments, R₁₃ is —CD₃.

In further embodiments, R₂ is not CH₃. In other embodiments, R₇ is not—CH₃, in some embodiments, R₁₂ is not —CH₃. In yet other embodiments,R₁₃ is not —CH₃.

In further embodiments, R₂ is not CDH₂. In other embodiments, R₇ is not—CDH₂, in some embodiments, R₁₂ is not —CDH₂. In yet other embodiments,R₁₃ is not CDH₂.

In further embodiments, R₂ is not —CD₂H. In other embodiments, R₇ is not—CD₂H, in some embodiments, R₁₂ is not —CD₂H. In yet other embodiments,R₁₃ is not —CD₂H.

In further embodiments, R₂ is not —CD₃. In other embodiments, R₇ is not—CD₃, in some embodiments, R₁₂ is not —CD₃. In yet other embodiments,R₁₃ is not —CD₃.

In one aspect, are pharmaceutical compositions comprising a compound ofFormula 1, including a single enantiomer, a mixture of the(+)-enantiomer and the (−)-enantiomer, a mixture of about 90% or more byweight of the (−)-enantiomer and about 10% or less by weight of the(+)-enantiomer, a mixture of about 90% or more by weight of the(+)-enantiomer and about 10% or less by weight of the (−)-enantiomer, anindividual diastereomer, or a mixture of diastereomers thereof; or apharmaceutically acceptable salt, solvate, or prodrug thereof, and oneor more pharmaceutically acceptable excipients or carriers.

In other embodiments, are pharmaceutical compositions comprising acompound of Formula 1, including a single enantiomer, a mixture of the(+)-enantiomer and the (−)-enantiomer, a mixture of about 90% or more byweight of the (−)-enantiomer and about 10% or less by weight of the(+)-enantiomer, a mixture of about 90% or more by weight of the(+)-enantiomer and about 10% or less by weight of the (−)-enantiomer, anindividual diastereomer, or a mixture of diastereomers thereof; or apharmaceutically acceptable salt, solvate, or prodrug thereof, and oneor more pharmaceutically acceptable excipients or carriers for thetreatment of conditions involving hypnosis.

In other embodiments, are pharmaceutical compositions comprising acompound of Formula 1, including a single enantiomer, a mixture of the(+)-enantiomer and the (−)-enantiomer, a mixture of about 90% or more byweight of the (−)-enantiomer and about 10% or less by weight of the(+)-enantiomer, a mixture of about 90% or more by weight of the(+)-enantiomer and about 10% or less by weight of the (−)-enantiomer, anindividual diastereomer, or a mixture of diastereomers thereof; or apharmaceutically acceptable salt, solvate, or prodrug thereof, and oneor more pharmaceutically acceptable excipients or carriers for thetreatment of conditions related to sleep.

In another aspect, is a method of modulating a benzodiazepine receptor,comprising administering a compound of Formula 1 or the (−)-enantiomerof the compound of Formula 1, or the (+)-enantiomer of the compound ofFormula 1.

In one aspect is a method of treating a mammalian subject, having,suspected of having, or being prone to a disease or condition involvinga benzodiazepine receptor, comprising administering to a mammaliansubject in need thereof a therapeutically effective amount of a compoundof Formula 1, or a pharmaceutically acceptable salt, solvate, or prodrugthereof.

In certain embodiments, the compound of Formula 1 contains about 60% ormore by weight of the (−)-enantiomer of the compound and about 40% orless by weight of (+)-enantiomer of the compound. In other embodiments,the compound of Formula 1 contains about 70% or more by weight of the(−)-enantiomer of the compound and about 30% or less by weight of(+)-enantiomer of the compound. In certain embodiments, the compound ofFormula 1 contains about 80% or more by weight of the (−)-enantiomer ofthe compound and about 20% or less by weight of (+)-enantiomer of thecompound. In some embodiments, the compound of Formula 1 contains about90% or more by weight of the (−)-enantiomer of the compound and about10% or less by weight of the (+)-enantiomer of the compound. In otherembodiments, the compound of Formula 1 contains about 95% or more byweight of the (−)-enantiomer of the compound and about 5% or less byweight of (+)-enantiomer of the compound. In certain embodiments, thecompound of Formula 1 contains about 99% or more by weight of the(−)-enantiomer of the compound and about 1% or less by weight of(+)-enantiomer of the compound.

In certain embodiments, the compound of Formula 1 contains about 60% ormore by weight of the (+)-enantiomer of the compound and about 40% orless by weight of (−)-enantiomer of the compound. In other embodiments,the compound of Formula 1 contains about 70% or more by weight of the(+)-enantiomer of the compound and about 30% or less by weight of(−)-enantiomer of the compound. In certain embodiments, the compound ofFormula 1 contains about 80% or more by weight of the (+)-enantiomer ofthe compound and about 20% or less by weight of (−)-enantiomer of thecompound. In some embodiments, the compound of Formula 1 contains about90% or more by weight of the (+)-enantiomer of the compound and about10% or less by weight of the (−)-enantiomer of the compound. In otherembodiments, the compound of Formula 1 contains about 95% or more byweight of the (+)-enantiomer of the compound and about 5% or less byweight of (−)-enantiomer of the compound. In certain embodiments, thecompound of Formula 1 contains about 99% or more by weight of the(+)-enantiomer of the compound and about 1% or less by weight of(−)-enantiomer of the compound.

The deuterated compound of Formula 1 may also contain less prevalentisotopes for other elements, including, but not limited to, ¹³C or ¹⁴Cfor carbon, ³³S, ³⁴S, or ³⁶S for sulfur, ¹⁵N for nitrogen, and ¹⁷O or¹⁸O for oxygen.

In certain embodiments, without being bound by any theory, the compoundprovided herein may expose a patient to a maximum of about 0.000005% D₂Oor about 0.00001% DHO, assuming that all of the C-D bonds in thecompound of Formula 1 are metabolized and released as D₂O or DHO. Thisquantity is a small fraction of the naturally occurring backgroundlevels of D₂O or DHO in circulation. In certain embodiments, the levelsof D₂O shown to cause toxicity in animals is much greater than even themaximum limit of exposure because of the deuterium enriched compound ofFormula 1. Thus, in certain embodiments, the deuterium-enriched compoundprovided herein should not cause any additional toxicity because of theuse of deuterium.

In one embodiment, the deuterated compounds provided herein maintain thebeneficial aspects of the corresponding non-isotopically enrichedmolecules while substantially increasing the maximum tolerated dose,decreasing toxicity, increasing the half-life (T_(1/2)), lowering themaximum plasma concentration (C_(max)) of the minimum efficacious dose(MED), lowering the efficacious dose and thus decreasing thenon-mechanism-related toxicity, and/or lowering the probability ofdrug-drug interactions.

Isotopic hydrogen can be introduced into a compound of Formula 1 asprovided herein by synthetic techniques that employ deuterated reagents,whereby incorporation rates are pre-determined; and/or by exchangetechniques, wherein incorporation rates are determined by equilibriumconditions, and may be highly variable depending on the reactionconditions. Synthetic techniques, where tritium or deuterium is directlyand specifically inserted by tritiated or deuterated reagents of knownisotopic content, may yield high tritium or deuterium abundance, but canbe limited by the chemistry required. In addition, the molecule beinglabeled may be changed, depending upon the severity of the syntheticreaction employed. Exchange techniques, on the other hand, may yieldlower tritium or deuterium incorporation, often with the isotope beingdistributed over many sites on the molecule, but offer the advantagethat they do not require separate synthetic steps and are less likely todisrupt the structure of the molecule being labeled.

The compounds of Formula 1 as provided herein can be prepared by methodsknown to one of skill in the art or following procedures similar tothose described in the Example section herein and routine modificationsthereof. For an example, the compound of Formula 1 can be prepared asshown in Scheme 1.

Toluene 2 is treated with acetic anhydride and aluminum trichloride atan elevated temperature to give ketone 3, which reacts withtetrabutylammonium tribromide to give bromoketone 4. Compound 4 iscoupled with aminopyridine 5 at an elevated temperature to giveimidazopyridine 6. Treatment of compound 6 withN,N-dimethyl-2-oxo-acetamide hemihydrate at an elevated temperatureaffords amide 7, which is reacted with phosphorus tribromide at anelevated temperature to produce the compound of Formula 1.

Deuterium can be incorporated to different positions synthetically,according to the synthetic procedures as shown in Scheme 1, by usingappropriate deuterated intermediates. For example, to introducedeuterium at one or more positions selected from R₁, R₂, R₃, and R₄aminopyridine 5 with the corresponding deuterium substitutions can beused. To introduce deuterium at one or more positions selected from R₅,R₆, R₇, R₉, and R₉, toluene 2 with the corresponding deuteriumsubstitutions can be used. To introduce deuterium at one or morepositions of R₁₂ and R₁₃, N,N-dimethyl-2-oxo-acetamide hemihydrate withthe corresponding deuterium substitutions can be used. These deuteratedintermediates are either commercially available, or can be prepared bymethods known to one of skill in the art or following procedures similarto those described in the Example section herein and routinemodifications thereof.

Deuterium can also be incorporated to various positions having anexchangeable proton, such as the alpha position to the cabonyl, viaproton-deuterium equilibrium exchange. To introduce deuterium at R₁₀ andR₁₁, these protons may be replaced with deuterium selectively ornon-selectively through a proton-deuterium exchange method known in theart.

It is to be understood that the compounds provided herein may containone or more chiral centers, chiral axes, and/or chiral planes, asdescribed in “Stereochemistry of Carbon Compounds” Eliel and Wilen, JohnWiley & Sons, New York, 1994, pp. 1119-1190. Such chiral centers, chiralaxes, and chiral planes may be of either the (R) or (S) configuration,or may be a mixture thereof.

Another method for characterizing a composition containing a compoundhaving at least one chiral center is by the effect of the composition ona beam of polarized light. When a beam of plane polarized light ispassed through a solution of a chiral compound, the plane ofpolarization of the light that emerges is rotated relative to theoriginal plane. This phenomenon is known as optical activity, andcompounds that rotate the plane of polarized light are said to beoptically active. One enantiomer of a compound will rotate the beam ofpolarized light in one direction, and the other enantiomer will rotatethe beam of light in the opposite direction. The enantiomer that rotatesthe polarized light in the clockwise direction is the (+)-enantiomer,and the enantiomer that rotates the polarized light in thecounterclockwise direction is the (−)-enantiomer. Included within thescope of the compositions described herein are compositions containingbetween 0 and 100% of the (+) and/or (−)-enantiomer of compounds ofFormula 1.

Where a compound of Formula 1 contains an alkenyl or alkenylene group,the compound may exist as one or mixture of geometric cis/trans (or Z/E)isomers. Where structural isomers are interconvertible via a low energybarrier, the compound of Formula 1 may exist as a single tautomer or amixture of tautomers. This can take the form of proton tautomerism inthe compound of Formula 1 that contains for example, an imino, keto, oroxime group; or so-called valence tautomerism in the compound thatcontain an aromatic moiety. It follows that a single compound mayexhibit more than one type of isomerism.

The compounds provided herein may be enantiomerically pure, such as asingle enantiomer or a single diastereomer, or be stereoisomericmixtures, such as a mixture of enantiomers, a racemic mixture, or adiastereomeric mixture. As such, one of skill in the art will recognizethat administration of a compound in its (R) form is equivalent, forcompounds that undergo epimerization in vivo, to administration of thecompound in its (S) form. Conventional techniques for thepreparation/isolation of individual enantiomers include chiral synthesisfrom a suitable optically pure precursor or resolution of the racemateusing, for example, chiral chromatography, recrystallization,resolution, diastereomeric salt formation, or derivatization intodiastereomeric adducts followed by separation.

When the compound of Formula 1 contains an acidic or basic moiety, itmay also be provided as a pharmaceutically acceptable salt (See, Bergeet al., J. Pharm. Sci. 1977, 66, 1-19; and “Handbook of PharmaceuticalSalts, Properties, and Use,” Stah and Wermuth, Ed.; Wiley-VCH and VHCA,Zurich, 2002).

Suitable acids for use in the preparation of pharmaceutically acceptablesalts include, but are not limited to, acetic acid, 2,2-dichloroaceticacid, acylated amino acids, adipic acid, alginic acid, ascorbic acid,L-aspartic acid, benzenesulfonic acid, benzoic acid, 4-acetamidobenzoicacid, boric acid, (+)-camphoric acid, camphorsulfonic acid,(+)-(1S)-camphor-10-sulfonic acid, capric acid, caproic acid, caprylicacid, cinnamic acid, citric acid, cyclamic acid, cyclohexanesulfamicacid, dodecylsulfuric acid, ethane-1,2-disulfonic acid, ethanesulfonicacid, 2-hydroxy-ethanesulfonic acid, formic acid, fumaric acid,galactaric acid, gentisic acid, glucoheptonic acid, D-gluconic acid,D-glucuronic acid, L-glutamic acid, α-oxo-glutaric acid, glycolic acid,hippuric acid, hydrobromic acid, hydrochloric acid, hydroiodic acid,(+)-L-lacetic acid, (±)-DL-lacetic acid, lactobionic acid, lauric acid,maleic acid, (−)-L-malic acid, malonic acid, (+)-DL-mandelic acid,methanesulfonic acid, naphthalene-2-sulfonic acid,naphthalene-1,5-disulfonic acid, 1-hydroxy-2-naphthoic acid, nicotinicacid, nitric acid, oleic acid, orotic acid, oxalic acid, palmitic acid,pamoic acid, perchloric acid, phosphoric acid, L-pyroglutamic acid,saccharic acid, salicylic acid, 4-amino-salicylic acid, sebacic acid,stearic acid, succinic acid, sulfuric acid, tannic acid, (+)-L-tartaricacid, thiocyanic acid, p-toluenesulfonic acid, undecylenic acid, andvaleric acid.

Suitable bases for use in the preparation of pharmaceutically acceptablesalts, including, but not limited to, inorganic bases, such as magnesiumhydroxide, calcium hydroxide, potassium hydroxide, zinc hydroxide, orsodium hydroxide; and organic bases, such as primary, secondary,tertiary, and quaternary, aliphatic and aromatic amines, includingL-arginine, benethamine, benzathine, choline, deanol, diethanolamine,diethylamine, dimethylamine, dipropylamine, diisopropylamine,2-(diethylamino)-ethanol, ethanolamine, ethylamine, ethylenediamine,isopropylamine, N-methyl-glucamine, hydrabamine, 1H-imidazole, L-lysine,morpholine, 4-(2-hydroxyethyl)-morpholine, methylamine, piperidine,piperazine, propylamine, pyrrolidine, 1-(2-hydroxyethyl)-pyrrolidine,pyridine, quinuclidine, quinoline, isoquinoline, secondary amines,triethanolamine, trimethylamine, triethylamine, N-methyl-D-glucamine,2-amino-2-(hydroxymethyl)-1,3-propanediol, and tromethamine.

The compound of Formula 1 may also be provided as a prodrug, which is afunctional derivative of the compound of Formula 1 and is readilyconvertible into the parent compound in vivo. Prodrugs are often usefulbecause, in some situations, they may be easier to administer than theparent compound. They may, for instance, be bioavailable by oraladministration whereas the parent compound is not. The prodrug may alsohave enhanced solubility in pharmaceutical compositions over the parentcompound. A prodrug may be converted into the parent drug by variousmechanisms, including enzymatic processes and metabolic hydrolysis. SeeHarper, Progress in Drug Research 1962, 4, 221-294; Morozowich et al. in“Design of Biopharmaceutical Properties through Prodrugs and Analogs,”Roche Ed., APHA Acad. Pharm Sci. 1977; “Bioreversible Carriers in Drugin Drug Design, Theory and Application,” Roche Ed., APHA Acad. Pharm.Sci. 1987; “Design of Prodrugs,” Bundgaard, Elsevier, 1985; Wang et al.,Curr. Pharm. Design 1999, 5, 265-287; Pauletti et al., Adv. Drug.Delivery Rev. 1997, 27, 235-256; Mizen et al., Pharm. Biotech. 1998, 11,345-365; Gaignault et al., Pract. Med. Chem. 1996, 671-696; Asgharnejadin “Transport Processes in Pharmaceutical Systems,” Amidon et al., Ed.,Marcell Dekker, 185-218, 2000; Balant et al., Eur. J. Drug Metab.Pharmacokinet. 1990, 15, 143-53; Balimane and Sinko, Adv. Drug DeliveryRev. 1999, 39, 183-209; Browne, Clin. Neuropharmacol. 1997, 20, 1-12;Bundgaard, Arch. Pharm. Chem. 1979, 86, 1-39; Bundgaard, Controlled DrugDelivery 1987, 17, 179-96; Bundgaard, Adv. Drug Delivery Rev. 1992, 8,1-38; Fleisher et al., Adv. Drug Delivery Rev. 1996, 19, 115-130;Fleisher et al., Methods Enzymol. 1985, 112, 360-381; Farquhar et al.,J. Pharm. Sci. 1983, 72, 324-325; Freeman et al., J. Chem. Soc., Chem.Commun. 1991, 875-877; Friis and Bundgaard, Eur. J. Pharm. Sci. 1996, 4,49-59; Gangwar et al., Des. Biopharm. Prop. Prodrugs Analogs, 1977,409-421; Nathwani and Wood, Drugs 1993, 45, 866-94; Sinhababu andThakker, Adv. Drug Delivery Rev. 1996, 19, 241-273; Stella et al., Drugs1985, 29, 455-73; Tan et al., Adv. Drug Delivery Rev. 1999, 39, 117-151;Taylor, Adv. Drug Delivery Rev. 1996, 19, 131-148; Valentino andBorchardt, Drug Discovery Today 1997, 2, 148-155; Wiebe and Knaus, Adv.Drug Delivery Rev. 1999, 39, 63-80; Waller et al., Br. J. Clin. Pharmac.1989, 28, 497-507.

Pharmaceutical Compositions

Provided herein are pharmaceutical compositions comprising a compound ofFormula 1 as an active ingredient, including a single enantiomer, amixture of the (+)-enantiomer and the (−)-enantiomer, a mixture of about90% or more by weight of the (−)-enantiomer and about 10% or less byweight of the (+)-enantiomer, a mixture of about 90% or more by weightof the (+)-enantiomer and about 10% or less by weight of the(−)-enantiomer, an individual diastereomer, or a mixture ofdiastereomers thereof; or a pharmaceutically acceptable salt, solvate,or prodrug thereof, in a pharmaceutically acceptable vehicle, carrier,diluent, or excipient, or a mixture thereof; and one or morepharmaceutically acceptable excipients or carriers.

Also provided herein are pharmaceutical compositions in modified releasedosage forms, which comprise a compound of Formula 1, including a singleenantiomer, a mixture of the (+)-enantiomer and the (−)-enantiomer, amixture of about 90% or more by weight of the (−)-enantiomer and about10% or less by weight of the (+)-enantiomer, a mixture of about 90% ormore by weight of the (+)-enantiomer and about 10% or less by weight ofthe (−)-enantiomer, an individual diastereomer, or a mixture ofdiastereomers thereof; or a pharmaceutically acceptable salt, solvate,or prodrug thereof; and one or more release controlling excipients asdescribed herein. Suitable modified release dosage vehicles include, butare not limited to, hydrophilic or hydrophobic matrix devices,water-soluble separating layer coatings, enteric coatings, osmoticdevices, multi-particulate devices, and combinations thereof. Thepharmaceutical compositions may also comprise non-release controllingexcipients.

Further, provided herein are pharmaceutical compositions in entericcoated dosage forms, which comprise a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; and one or more release controllingexcipients for use in an enteric coated dosage form. The pharmaceuticalcompositions may also comprise non-release controlling excipients.

Additionally, provided herein are pharmaceutical compositions ineffervescent dosage forms, which comprise the compounds of Formula 1,including a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; and one or more release controllingexcipients for use in an enteric coated dosage form. The pharmaceuticalcompositions may also comprise non-release controlling excipients.

Further, provided herein are pharmaceutical compositions in a dosageform that has an instant releasing component and at least one delayedreleasing component, and is capable of giving a discontinuous release ofthe compound in the form of at least two consecutive pulses separated intime from 0.1 up to 24 hours. The pharmaceutical compositions comprise acompound of Formula 1, including a single enantiomer, a mixture of the(+)-enantiomer and the (−)-enantiomer, a mixture of about 90% or more byweight of the (−)-enantiomer and about 10% or less by weight of the(+)-enantiomer, a mixture of about 90% or more by weight of the(+)-enantiomer and about 10% or less by weight of the (−)-enantiomer, anindividual diastereomer, or a mixture of diastereomers thereof; or apharmaceutically acceptable salt, solvate, or prodrug thereof; and oneor more release controlling and non-release controlling excipients, suchas those excipients suitable for a disruptable semi-permeable membraneand as swellable substances.

Provided herein also are pharmaceutical compositions in a dosage formfor oral administration to a subject, which comprises a compound ofFormula 1, including a single enantiomer, a mixture of the(+)-enantiomer and the (−)-enantiomer, a mixture of about 90% or more byweight of the (−)-enantiomer and about 10% or less by weight of the(+)-enantiomer, a mixture of about 90% or more by weight of the(+)-enantiomer and about 10% or less by weight of the (−)-enantiomer, anindividual diastereomer, or a mixture of diastereomers thereof; or apharmaceutically acceptable salt, solvate, or prodrug thereof; and oneor more pharmaceutically acceptable excipients or carriers, enclosed inan intermediate reactive layer comprising a gastric juice-resistantpolymeric layered material partially neutralized with alkali and havingcation exchange capacity and a gastric juice-resistant outer layer.

Provided herein are pharmaceutical compositions that comprise about 0.1to about 100 mg, about 0.5 to about 50 mg, about 1 to about 20 mg, about1 mg, about 2 mg, about 3 mg, about 4 mg, about 5 mg, about 6 mg, about7 mg, about 8 mg, about 10 mg, about 15 mg, about 20 mg of one or morecompounds of Formula I in the form of tablets for oral administration.The pharmaceutical compositions further comprise hydroxypropylmethylcellulose, lactose, magnesium stearate, micro-crystallinecellulose, polyethylene glycol, sodium starch glycolate, titaniumdioxide, and polysorbate 80.

Provided herein are pharmaceutical compositions that comprise about 0.1to about 100 mg, about 0.5 to about 50 mg, about 1 to about 20 mg, about1 mg, about 2 mg, about 3 mg, about 4 mg, about 5 mg, about 6 mg, about7 mg, about 8 mg, about 10 mg, about 15 mg, about 20 mg of one or morecompounds of Formula I in the form of coated two-layer tablet for oraladministration: one layer that releases a compound of Formula 1immediately and another layer that allows a slower release of additionalcompound of Formula 1. The pharmaceutical compositions further comprisecolloidal silicon dioxide, hypromellose, lactose monohydrate, magnesiumstearate, microcrystalline cellulose, polyethylene glycol, potassiumbitartrate, sodium starch glycolate, and titanium dioxide.

The pharmaceutical compositions provided herein may be provided inunit-dosage forms or multiple-dosage forms. Unit-dosage forms, as usedherein, refer to physically discrete units suitable for administrationto human and animal subjects and packaged individually as is known inthe art. Each unit-dose contains a predetermined quantity of the activeingredient(s) sufficient to produce the desired therapeutic effect, inassociation with the required pharmaceutical carriers or excipients.Examples of unit-dosage forms include ampules, syringes, andindividually packaged tablets and capsules. Unit-dosage forms may beadministered in fractions or multiples thereof. A multiple-dosage formis a plurality of identical unit-dosage forms packaged in a singlecontainer to be administered in segregated unit-dosage form. Examples ofmultiple-dosage forms include vials, bottles of tablets or capsules, orbottles of pints or gallons.

The compound of Formula 1 provided herein may be administered alone, orin combination with one or more other compounds provided herein, one ormore other active ingredients. The pharmaceutical compositions thatcomprise a compound provided herein may be formulated in various dosageforms for oral, parenteral, and topical administration. Thepharmaceutical compositions may also be formulated as a modified releasedosage form, including delayed-, extended-, prolonged-, sustained-,pulsatile-, controlled-, accelerated- and fast-, targeted-,programmed-release, and gastric retention dosage forms. These dosageforms can be prepared according to conventional methods and techniquesknown to those skilled in the art (see, Remington: The Science andPractice of Pharmacy, supra; Modified-Release Drug Deliver Technology,Rathbone et al., Eds., Drugs and the Pharmaceutical Science, MarcelDekker, Inc.: New York, N.Y., 2002; Vol. 126).

The pharmaceutical compositions provided herein may be administered atonce, or multiple times at intervals of time. It is understood that theprecise dosage and duration of treatment may vary with the age, weight,and condition of the patient being treated, and may be determinedempirically using known testing protocols or by extrapolation from invivo or in vitro test or diagnostic data. It is further understood thatfor any particular individual, specific dosage regimens should beadjusted over time according to the individual need and the professionaljudgment of the person administering or supervising the administrationof the formulations.

In the case wherein the patient's condition does not improve, upon thedoctor's discretion the administration of the compounds may beadministered chronically, that is, for an extended period of time,including throughout the duration of the patient's life in order toameliorate or otherwise control or limit the symptoms of the patient'sdisease or condition.

In the case wherein the patient's status does improve, upon the doctor'sdiscretion the administration of the compounds may be given continuouslyor temporarily suspended for a certain length of time (i.e., a “drugholiday”).

Once improvement of the patient's conditions has occurred, a maintenancedose is administered if necessary. Subsequently, the dosage or thefrequency of administration, or both, can be reduced, as a function ofthe symptoms, to a level at which the improved disease, disorder orcondition is retained. Patients can, however, require intermittenttreatment on a long-term basis upon any recurrence of symptoms.

A. Oral Administration

The pharmaceutical compositions provided herein may be provided insolid, semisolid, or liquid dosage forms for oral administration. Asused herein, oral administration also include buccal, lingual, andsublingual administration. Suitable oral dosage forms include, but arenot limited to, tablets, capsules, pills, troches, lozenges, pastilles,cachets, pellets, medicated chewing gum, granules, bulk powders,effervescent or non-effervescent powders or granules, solutions,emulsions, suspensions, solutions, wafers, sprinkles, elixirs, andsyrups. In addition to the active ingredient(s), the pharmaceuticalcompositions may contain one or more pharmaceutically acceptablecarriers or excipients, including, but not limited to, binders, fillers,diluents, disintegrants, wetting agents, lubricants, glidants, coloringagents, dye-migration inhibitors, sweetening agents, and flavoringagents.

Binders or granulators impart cohesiveness to a tablet to ensure thetablet remaining intact after compression. Suitable binders orgranulators include, but are not limited to, starches, such as cornstarch, potato starch, and pre-gelatinized starch (e.g., STARCH 1500);gelatin; sugars, such as sucrose, glucose, dextrose, molasses, andlactose; natural and synthetic gums, such as acacia, alginic acid,alginates, extract of Irish moss, Panwar gum, ghatti gum, mucilage ofisabgol husks, carboxymethylcellulose, methylcellulose,polyvinylpyrrolidone (PVP), Veegum, larch arabogalactan, powderedtragacanth, and guar gum; celluloses, such as ethyl cellulose, celluloseacetate, carboxymethyl cellulose calcium, sodium carboxymethylcellulose, methyl cellulose, hydroxyethylcellulose (HEC),hydroxypropylcellulose (HPC), hydroxypropyl methyl cellulose (HPMC);microcrystalline celluloses, such as AVICEL-PH-101, AVICEL-PH-103,AVICEL RC-581, AVICEL-PH-105 (FMC Corp., Marcus Hook, Pa.); and mixturesthereof. Suitable fillers include, but are not limited to, talc, calciumcarbonate, microcrystalline cellulose, powdered cellulose, dextrates,kaolin, mannitol, silicic acid, sorbitol, starch, pre-gelatinizedstarch, and mixtures thereof. The binder or filler may be present fromabout 50 to about 99% by weight in the pharmaceutical compositionsprovided herein.

Suitable diluents include, but are not limited to, dicalcium phosphate,calcium sulfate, lactose, sorbitol, sucrose, inositol, cellulose,kaolin, mannitol, sodium chloride, dry starch, and powdered sugar.Certain diluents, such as mannitol, lactose, sorbitol, sucrose, andinositol, when present in sufficient quantity, can impart properties tosome compressed tablets that permit disintegration in the mouth bychewing. Such compressed tablets can be used as chewable tablets.

Suitable disintegrants include, but are not limited to, agar; bentonite;celluloses, such as methylcellulose and carboxymethylcellulose; woodproducts; natural sponge; cation-exchange resins; alginic acid; gums,such as guar gum and Veegum HV; citrus pulp; cross-linked celluloses,such as croscarmellose; cross-linked polymers, such as crospovidone;cross-linked starches; calcium carbonate; microcrystalline cellulose,such as sodium starch glycolate; polacrilin potassium; starches, such ascorn starch, potato starch, tapioca starch, and pre-gelatinized starch;clays; aligns; and mixtures thereof. The amount of disintegrant in thepharmaceutical compositions provided herein varies upon the type offormulation, and is readily discernible to those of ordinary skill inthe art. The pharmaceutical compositions provided herein may containfrom about 0.5 to about 15% or from about 1 to about 5% by weight of adisintegrant.

Suitable lubricants include, but are not limited to, calcium stearate;magnesium stearate; mineral oil; light mineral oil; glycerin; sorbitol;mannitol; glycols, such as glycerol behenate and polyethylene glycol(PEG); stearic acid; sodium lauryl sulfate; talc; hydrogenated vegetableoil, including peanut oil, cottonseed oil, sunflower oil, sesame oil,olive oil, corn oil, and soybean oil; zinc stearate; ethyl oleate; ethyllaureate; agar; starch; lycopodium; silica or silica gels, such asAEROSIL®200 (W.R. Grace Co., Baltimore, Md.) and CAB-O-SIL® (Cabot Co.of Boston, Mass.); and mixtures thereof. The pharmaceutical compositionsprovided herein may contain about 0.1 to about 5% by weight of alubricant.

Suitable glidants include colloidal silicon dioxide, CAB-O-SIL® (CabotCo. of Boston, Mass.), and asbestos-free talc. Coloring agents includeany of the approved, certified, water soluble FD&C dyes, and waterinsoluble FD&C dyes suspended on alumina hydrate, and color lakes andmixtures thereof. A color lake is the combination by adsorption of awater-soluble dye to a hydrous oxide of a heavy metal, resulting in aninsoluble form of the dye. Flavoring agents include natural flavorsextracted from plants, such as fruits, and synthetic blends of compoundswhich produce a pleasant taste sensation, such as peppermint and methylsalicylate. Sweetening agents include sucrose, lactose, mannitol,syrups, glycerin, and artificial sweeteners, such as saccharin andaspartame. Suitable emulsifying agents include gelatin, acacia,tragacanth, bentonite, and surfactants, such as polyoxyethylene sorbitanmonooleate (TWEEN® 20), polyoxyethylene sorbitan monooleate 80 (TWEEN®80), and triethanolamine oleate. Suspending and dispersing agentsinclude sodium carboxymethylcellulose, pectin, tragacanth, Veegum,acacia, sodium carbomethylcellulose, hydroxypropyl methylcellulose, andpolyvinylpyrolidone. Preservatives include glycerin, methyl andpropylparaben, benzoic add, sodium benzoate and alcohol. Wetting agentsinclude propylene glycol monostearate, sorbitan monooleate, diethyleneglycol monolaurate, and polyoxyethylene lauryl ether. Solvents includeglycerin, sorbitol, ethyl alcohol, and syrup. Examples of non-aqueousliquids utilized in emulsions include mineral oil and cottonseed oil.Organic acids include citric and tartaric acid. Sources of carbondioxide include sodium bicarbonate and sodium carbonate.

It should be understood that many carriers and excipients may serveseveral functions, even within the same formulation.

The pharmaceutical compositions provided herein may be provided ascompressed tablets, tablet triturates, chewable lozenges, rapidlydissolving tablets, multiple compressed tablets, or enteric-coatingtablets, sugar-coated, or film-coated tablets. Enteric-coated tabletsare compressed tablets coated with substances that resist the action ofstomach acid but dissolve or disintegrate in the intestine, thusprotecting the active ingredients from the acidic environment of thestomach. Enteric-coatings include, but are not limited to, fatty acids,fats, phenylsalicylate, waxes, shellac, ammoniated shellac, andcellulose acetate phthalates. Sugar-coated tablets are compressedtablets surrounded by a sugar coating, which may be beneficial incovering up objectionable tastes or odors and in protecting the tabletsfrom oxidation. Film-coated tablets are compressed tablets that arecovered with a thin layer or film of a water-soluble material. Filmcoatings include, but are not limited to, hydroxyethylcellulose, sodiumcarboxymethylcellulose, polyethylene glycol 4000, and cellulose acetatephthalate. Film coating imparts the same general characteristics assugar coating. Multiple compressed tablets are compressed tablets madeby more than one compression cycle, including layered tablets, andpress-coated or dry-coated tablets.

The tablet dosage forms may be prepared from the active ingredient inpowdered, crystalline, or granular forms, alone or in combination withone or more carriers or excipients described herein, including binders,disintegrants, controlled-release polymers, lubricants, diluents, and/orcolorants. Flavoring and sweetening agents are especially useful in theformation of chewable tablets and lozenges.

The pharmaceutical compositions provided herein may be provided as softor hard capsules, which can be made from gelatin, methylcellulose,starch, or calcium alginate. The hard gelatin capsule, also known as thedry-filled capsule (DFC), consists of two sections, one slipping overthe other, thus completely enclosing the active ingredient. The softelastic capsule (SEC) is a soft, globular shell, such as a gelatinshell, which is plasticized by the addition of glycerin, sorbitol, or asimilar polyol. The soft gelatin shells may contain a preservative toprevent the growth of microorganisms. Suitable preservatives are thoseas described herein, including methyl- and propyl-parabens, and sorbicacid. The liquid, semisolid, and solid dosage forms provided herein maybe encapsulated in a capsule. Suitable liquid and semisolid dosage formsinclude solutions and suspensions in propylene carbonate, vegetableoils, or triglycerides. Capsules containing such solutions can beprepared as described in U.S. Pat. Nos. 4,328,245; 4,409,239; and4,410,545. The capsules may also be coated as known by those of skill inthe art in order to modify or sustain dissolution of the activeingredient.

The pharmaceutical compositions provided herein may be provided inliquid and semisolid dosage forms, including emulsions, solutions,suspensions, elixirs, and syrups. An emulsion is a two-phase system, inwhich one liquid is dispersed in the form of small globules throughoutanother liquid, which can be oil-in-water or water-in-oil. Emulsions mayinclude a pharmaceutically acceptable non-aqueous liquids or solvent,emulsifying agent, and preservative. Suspensions may include apharmaceutically acceptable suspending agent and preservative. Aqueousalcoholic solutions may include a pharmaceutically acceptable acetal,such as a di(lower alkyl) acetal of a lower alkyl aldehyde (the term“lower” means an alkyl having between 1 and 6 carbon atoms), e.g.,acetaldehyde diethyl acetal; and a water-miscible solvent having one ormore hydroxyl groups, such as propylene glycol and ethanol. Elixirs areclear, sweetened, and hydroalcoholic solutions. Syrups are concentratedaqueous solutions of a sugar, for example, sucrose, and may also containa preservative. For a liquid dosage form, for example, a solution in apolyethylene glycol may be diluted with a sufficient quantity of apharmaceutically acceptable liquid carrier, e.g., water, to be measuredconveniently for administration.

Other useful liquid and semisolid dosage forms include, but are notlimited to, those containing the active ingredient(s) provided herein,and a dialkylated mono- or poly-alkylene glycol, including,1,2-dimethoxymethane, diglyme, triglyme, tetraglyme, polyethyleneglycol-350-dimethyl ether, polyethylene glycol-550-dimethyl ether,polyethylene glycol-750-dimethyl ether, wherein 350, 550, and 750 referto the approximate average molecular weight of the polyethylene glycol.These formulations may further comprise one or more antioxidants, suchas butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA),propyl gallate, vitamin E, hydroquinone, hydroxycoumarins, ethanolamine,lecithin, cephalin, ascorbic acid, malic acid, sorbitol, phosphoricacid, bisulfite, sodium metabisulfite, thiodipropionic acid and itsesters, and dithiocarbamates.

The pharmaceutical compositions provided herein for oral administrationmay be also provided in the forms of liposomes, micelles, microspheres,or nanosystems. Micellar dosage forms can be prepared as described inU.S. Pat. No. 6,350,458.

The pharmaceutical compositions provided herein may be provided asnon-effervescent or effervescent, granules and powders, to bereconstituted into a liquid dosage form. Pharmaceutically acceptablecarriers and excipients used in the non-effervescent granules or powdersmay include diluents, sweeteners, and wetting agents. Pharmaceuticallyacceptable carriers and excipients used in the effervescent granules orpowders may include organic acids and a source of carbon dioxide.

Coloring and flavoring agents can be used in all of the above dosageforms.

The pharmaceutical compositions provided herein may be formulated asimmediate or modified release dosage forms, including delayed-,sustained, pulsed-, controlled, targeted-, and programmed-release forms.

The pharmaceutical compositions provided herein may be co-formulatedwith other active ingredients which do not impair the desiredtherapeutic action, or with substances that supplement the desiredaction, such as other GABA_(A) receptor modulators.

B. Parenteral Administration

The pharmaceutical compositions provided herein may be administeredparenterally by injection, infusion, or implantation, for local orsystemic administration. Parenteral administration, as used herein,include intravenous, intraarterial, intraperitoneal, intrathecal,intraventricular, intraurethral, intrasternal, intracranial,intramuscular, intrasynovial, and subcutaneous administration.

The pharmaceutical compositions provided herein may be formulated in anydosage forms that are suitable for parenteral administration, includingsolutions, suspensions, emulsions, micelles, liposomes, microspheres,nanosystems, and solid forms suitable for solutions or suspensions inliquid prior to injection. Such dosage forms can be prepared accordingto conventional methods known to those skilled in the art ofpharmaceutical science (see, Remington: The Science and Practice ofPharmacy, supra).

The pharmaceutical compositions intended for parenteral administrationmay include one or more pharmaceutically acceptable carriers andexcipients, including, but not limited to, aqueous vehicles,water-miscible vehicles, non-aqueous vehicles, antimicrobial agents orpreservatives against the growth of microorganisms, stabilizers,solubility enhancers, isotonic agents, buffering agents, antioxidants,local anesthetics, suspending and dispersing agents, wetting oremulsifying agents, complexing agents, sequestering or chelating agents,cryoprotectants, lyoprotectants, thickening agents, pH adjusting agents,and inert gases.

Suitable aqueous vehicles include, but are not limited to, water,saline, physiological saline or phosphate buffered saline (PBS), sodiumchloride injection, Ringers injection, isotonic dextrose injection,sterile water injection, dextrose and lactated Ringers injection.Non-aqueous vehicles include, but are not limited to, fixed oils ofvegetable origin, castor oil, corn oil, cottonseed oil, olive oil,peanut oil, peppermint oil, safflower oil, sesame oil, soybean oil,hydrogenated vegetable oils, hydrogenated soybean oil, and medium-chaintriglycerides of coconut oil, and palm seed oil. Water-miscible vehiclesinclude, but are not limited to, ethanol, 1,3-butanediol, liquidpolyethylene glycol (e.g., polyethylene glycol 300 and polyethyleneglycol 400), propylene glycol, glycerin, N-methyl-2-pyrrolidone,dimethylacetamide, and dimethylsulfoxide.

Suitable antimicrobial agents or preservatives include, but are notlimited to, phenols, cresols, mercurials, benzyl alcohol, chlorobutanol,methyl and propyl p-hydroxybenzates, thimerosal, benzalkonium chloride,benzethonium chloride, methyl- and propyl-parabens, and sorbic acid.Suitable isotonic agents include, but are not limited to, sodiumchloride, glycerin, and dextrose. Suitable buffering agents include, butare not limited to, phosphate and citrate. Suitable antioxidants arethose as described herein, including bisulfite and sodium metabisulfite.Suitable local anesthetics include, but are not limited to, procainehydrochloride. Suitable suspending and dispersing agents are those asdescribed herein, including sodium carboxymethylcelluose, hydroxypropylmethylcellulose, and polyvinylpyrrolidone. Suitable emulsifying agentsinclude those described herein, including polyoxyethylene sorbitanmonolaurate, polyoxyethylene sorbitan monooleate 80, and triethanolamineoleate. Suitable sequestering or chelating agents include, but are notlimited to EDTA. Suitable pH adjusting agents include, but are notlimited to, sodium hydroxide, hydrochloric acid, citric acid, andlacetic acid. Suitable complexing agents include, but are not limitedto, cyclodextrins, including α-cyclodextrin, β-cyclodextrin,hydroxypropyl-β-cyclodextrin, sulfobutylether-β-cyclodextrin, andsulfobutylether 7-β-cyclodextrin (CAPTISOL®, CyDex, Lenexa, Kans.).

The pharmaceutical compositions provided herein may be formulated forsingle or multiple dosage administration. The single dosage formulationsare packaged in an ampule, a vial, or a syringe. The multiple dosageparenteral formulations must contain an antimicrobial agent atbacteriostatic or fungistatic concentrations. All parenteralformulations must be sterile, as known and practiced in the art.

In one embodiment, the pharmaceutical compositions are provided asready-to-use sterile solutions. In another embodiment, thepharmaceutical compositions are provided as sterile dry solubleproducts, including lyophilized powders and hypodermic tablets, to bereconstituted with a vehicle prior to use. In yet another embodiment,the pharmaceutical compositions are provided as ready-to-use sterilesuspensions. In yet another embodiment, the pharmaceutical compositionsare provided as sterile dry insoluble products to be reconstituted witha vehicle prior to use. In still another embodiment, the pharmaceuticalcompositions are provided as ready-to-use sterile emulsions.

The pharmaceutical compositions provided herein may be formulated asimmediate or modified release dosage forms, including delayed-,sustained, pulsed-, controlled, targeted-, and programmed-release forms.

The pharmaceutical compositions may be formulated as a suspension,solid, semi-solid, or thixotropic liquid, for administration as animplanted depot. In one embodiment, the pharmaceutical compositionsprovided herein are dispersed in a solid inner matrix, which issurrounded by an outer polymeric membrane that is insoluble in bodyfluids but allows the active ingredient in the pharmaceuticalcompositions diffuse through.

Suitable inner matrixes include polymethylmethacrylate,polybutylmethacrylate, plasticized or unplasticized polyvinylchloride,plasticized nylon, plasticized polyethyleneterephthalate, naturalrubber, polyisoprene, polyisobutylene, polybutadiene, polyethylene,ethylene-vinylacetate copolymers, silicone rubbers,polydimethylsiloxanes, silicone carbonate copolymers, hydrophilicpolymers, such as hydrogels of esters of acrylic and methacrylic acid,collagen, cross-linked polyvinylalcohol, and cross-linked partiallyhydrolyzed polyvinyl acetate.

Suitable outer polymeric membranes include polyethylene, polypropylene,ethylene/propylene copolymers, ethylene/ethyl acrylate copolymers,ethylene/vinylacetate copolymers, silicone rubbers, polydimethylsiloxanes, neoprene rubber, chlorinated polyethylene, polyvinylchloride,vinylchloride copolymers with vinyl acetate, vinylidene chloride,ethylene and propylene, ionomer polyethylene terephthalate, butyl rubberepichlorohydrin rubbers, ethylene/vinyl alcohol copolymer,ethylene/vinyl acetate/vinyl alcohol terpolymer, andethylene/vinyloxyethanol copolymer.

C. Topical Administration

The pharmaceutical compositions provided herein may be administeredtopically to the skin, orifices, or mucosa. The topical administration,as used herein, include (intra)dermal, conjuctival, intracorneal,intraocular, ophthalmic, auricular, transdermal, nasal, vaginal,uretheral, respiratory, and rectal administration.

The pharmaceutical compositions provided herein may be formulated in anydosage forms that are suitable for topical administration for local orsystemic effect, including emulsions, solutions, suspensions, creams,gels, hydrogels, ointments, dusting powders, dressings, elixirs,lotions, suspensions, tinctures, pastes, foams, films, aerosols,irrigations, sprays, suppositories, bandages, dermal patches. Thetopical formulation of the pharmaceutical compositions provided hereinmay also comprise liposomes, micelles, microspheres, nanosystems, andmixtures thereof.

Pharmaceutically acceptable carriers and excipients suitable for use inthe topical formulations provided herein include, but are not limitedto, aqueous vehicles, water-miscible vehicles, non-aqueous vehicles,antimicrobial agents or preservatives against the growth ofmicroorganisms, stabilizers, solubility enhancers, isotonic agents,buffering agents, antioxidants, local anesthetics, suspending anddispersing agents, wetting or emulsifying agents, complexing agents,sequestering or chelating agents, penetration enhancers,cryopretectants, lyoprotectants, thickening agents, and inert gases.

The pharmaceutical compositions may also be administered topically byelectroporation, iontophoresis, phonophoresis, sonophoresis andmicroneedle or needle-free injection, such as POWDERJECT™ (Chiron Corp.,Emeryville, Calif.), and BIOJECT™ (Bioject Medical Technologies Inc.,Tualatin, Oreg.).

The pharmaceutical compositions provided herein may be provided in theforms of ointments, creams, and gels. Suitable ointment vehicles includeoleaginous or hydrocarbon vehicles, including such as lard, benzoinatedlard, olive oil, cottonseed oil, and other oils, white petrolatum;emulsifiable or absorption vehicles, such as hydrophilic petrolatum,hydroxystearin sulfate, and anhydrous lanolin; water-removable vehicles,such as hydrophilic ointment; water-soluble ointment vehicles, includingpolyethylene glycols of varying molecular weight; emulsion vehicles,either water-in-oil (W/O) emulsions or oil-in-water (O/W) emulsions,including cetyl alcohol, glyceryl monostearate, lanolin, and stearicacid (see, Remington: The Science and Practice of Pharmacy, supra).These vehicles are emollient but generally require addition ofantioxidants and preservatives.

Suitable cream base can be oil-in-water or water-in-oil. Cream vehiclesmay be water-washable, and contain an oil phase, an emulsifier, and anaqueous phase. The oil phase is also called the “internal” phase, whichis generally comprised of petrolatum and a fatty alcohol such as cetylor stearyl alcohol. The aqueous phase usually, although not necessarily,exceeds the oil phase in volume, and generally contains a humectant. Theemulsifier in a cream formulation may be a nonionic, anionic, cationic,or amphoteric surfactant.

Gels are semisolid, suspension-type systems. Single-phase gels containorganic macromolecules distributed substantially uniformly throughoutthe liquid carrier. Suitable gelling agents include crosslinked acrylicacid polymers, such as carbomers, carboxypolyalkylenes, Carbopol®;hydrophilic polymers, such as polyethylene oxides,polyoxyethylene-polyoxypropylene copolymers, and polyvinylalcohol;cellulosic polymers, such as hydroxypropyl cellulose, hydroxyethylcellulose, hydroxypropyl methylcellulose, hydroxypropyl methylcellulosephthalate, and methylcellulose; gums, such as tragacanth and xanthangum; sodium alginate; and gelatin. In order to prepare a uniform gel,dispersing agents such as alcohol or glycerin can be added, or thegelling agent can be dispersed by trituration, mechanical mixing, and/orstirring.

The pharmaceutical compositions provided herein may be administeredrectally, urethrally, vaginally, or perivaginally in the forms ofsuppositories, pessaries, bougies, poultices or cataplasm, pastes,powders, dressings, creams, plasters, contraceptives, ointments,solutions, emulsions, suspensions, tampons, gels, foams, sprays, orenemas. These dosage forms can be manufactured using conventionalprocesses as described in Remington: The Science and Practice ofPharmacy, supra.

Rectal, urethral, and vaginal suppositories are solid bodies forinsertion into body orifices, which are solid at ordinary temperaturesbut melt or soften at body temperature to release the activeingredient(s) inside the orifices. Pharmaceutically acceptable carriersutilized in rectal and vaginal suppositories include bases or vehicles,such as stiffening agents, which produce a melting point in theproximity of body temperature, when formulated with the pharmaceuticalcompositions provided herein; and antioxidants as described herein,including bisulfite and sodium metabisulfite. Suitable vehicles include,but are not limited to, cocoa butter (theobroma oil), glycerin-gelatin,carbowax (polyoxyethylene glycol), spermaceti, paraffin, white andyellow wax, and appropriate mixtures of mono-, di- and triglycerides offatty acids, hydrogels, such as polyvinyl alcohol, hydroxyethylmethacrylate, polyacrylic acid; glycerinated gelatin. Combinations ofthe various vehicles may be used. Rectal and vaginal suppositories maybe prepared by the compressed method or molding. The typical weight of arectal and vaginal suppository is about 2 to about 3 g.

The pharmaceutical compositions provided herein may be administeredophthalmically in the forms of solutions, suspensions, ointments,emulsions, gel-forming solutions, powders for solutions, gels, ocularinserts, and implants.

The pharmaceutical compositions provided herein may be administeredintranasally or by inhalation to the respiratory tract. Thepharmaceutical compositions may be provided in the form of an aerosol orsolution for delivery using a pressurized container, pump, spray,atomizer, such as an atomizer using electrohydrodynamics to produce afine mist, or nebulizer, alone or in combination with a suitablepropellant, such as 1,1,1,2-tetrafluoroethane or1,1,1,2,3,3,3-heptafluoropropane. The pharmaceutical compositions mayalso be provided as a dry powder for insufflation, alone or incombination with an inert carrier such as lactose or phospholipids; andnasal drops. For intranasal use, the powder may comprise a bioadhesiveagent, including chitosan or cyclodextrin.

Solutions or suspensions for use in a pressurized container, pump,spray, atomizer, or nebulizer may be formulated to contain ethanol,aqueous ethanol, or a suitable alternative agent for dispersing,solubilizing, or extending release of the active ingredient providedherein, a propellant as solvent; and/or an surfactant, such as sorbitantrioleate, oleic acid, or an oligolacetic acid.

The pharmaceutical compositions provided herein may be micronized to asize suitable for delivery by inhalation, such as about 50 micrometersor less, or about 10 micrometers or less. Particles of such sizes may beprepared using a comminuting method known to those skilled in the art,such as spiral jet milling, fluid bed jet milling, supercritical fluidprocessing to form nanoparticles, high pressure homogenization, or spraydrying.

Capsules, blisters and cartridges for use in an inhaler or insufflatormay be formulated to contain a powder mix of the pharmaceuticalcompositions provided herein; a suitable powder base, such as lactose orstarch; and a performance modifier, such as 1-leucine, mannitol, ormagnesium stearate. The lactose may be anhydrous or in the form of themonohydrate. Other suitable excipients include dextran, glucose,maltose, sorbitol, xylitol, fructose, sucrose, and trehalose. Thepharmaceutical compositions provided herein for inhaled/intranasaladministration may further comprise a suitable flavor, such as mentholand levomenthol, or sweeteners, such as saccharin or saccharin sodium.

The pharmaceutical compositions provided herein for topicaladministration may be formulated to be immediate release or modifiedrelease, including delayed-, sustained-, pulsed-, controlled-, targeted,and programmed release.

D. Modified Release

The pharmaceutical compositions provided herein may be formulated as amodified release dosage form. As used herein, the term “modifiedrelease” refers to a dosage form in which the rate or place of releaseof the active ingredient(s) is different from that of an immediatedosage form when administered by the same route. Modified release dosageforms include delayed-, extended-, prolonged-, sustained-, pulsatile-,controlled-, accelerated- and fast-, targeted-, programmed-release, andgastric retention dosage forms. The pharmaceutical compositions inmodified release dosage forms can be prepared using a variety ofmodified release devices and methods known to those skilled in the art,including, but not limited to, matrix controlled release devices,osmotic controlled release devices, multiparticulate controlled releasedevices, ion-exchange resins, enteric coatings, multilayered coatings,microspheres, liposomes, and combinations thereof. The release rate ofthe active ingredient(s) can also be modified by varying the particlesizes and polymorphorism of the active ingredient(s).

Examples of modified release include, but are not limited to, thosedescribed in U.S. Pat. Nos. 3,845,770; 3,916,899; 3,536,809; 3,598,123;4,008,719; 5,674,533; 5,059,595; 5,591,767; 5,120,548; 5,073,543;5,639,476; 5,354,556; 5,639,480; 5,733,566; 5,739,108; 5,891,474;5,922,356; 5,972,891; 5,980,945; 5,993,855; 6,045,830; 6,087,324;6,113,943; 6,197,350; 6,248,363; 6,264,970; 6,267,981; 6,376,461;6,419,961; 6,589,548; 6,613,358; and 6,699,500.

1. Matrix Controlled Release Devices

The pharmaceutical compositions provided herein in a modified releasedosage form may be fabricated using a matrix controlled release deviceknown to those skilled in the art (see, Takada et al. in “Encyclopediaof Controlled Drug Delivery,” Vol. 2, Mathiowitz ed., Wiley, 1999).

In one embodiment, the pharmaceutical compositions provided herein in amodified release dosage form is formulated using an erodible matrixdevice, which is water-swellable, erodible, or soluble polymers,including synthetic polymers, and naturally occurring polymers andderivatives, such as polysaccharides and proteins.

Materials useful in forming an erodible matrix include, but are notlimited to, chitin, chitosan, dextran, and pullulan; gum agar, gumarabic, gum karaya, locust bean gum, gum tragacanth, carrageenans, gumghatti, guar gum, xanthan gum, and scleroglucan; starches, such asdextrin and maltodextrin; hydrophilic colloids, such as pectin;phosphatides, such as lecithin; alginates; propylene glycol alginate;gelatin; collagen; and cellulosics, such as ethyl cellulose (EC),methylethyl cellulose (MEC), carboxymethyl cellulose (CMC), CMEC,hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), celluloseacetate (CA), cellulose propionate (CP), cellulose butyrate (CB),cellulose acetate butyrate (CAB), CAP, CAT, hydroxypropyl methylcellulose (HPMC), HPMCP, HPMCAS, hydroxypropyl methyl cellulose acetatetrimellitate (HPMCAT), and ethylhydroxy ethylcellulose (EHEC); polyvinylpyrrolidone; polyvinyl alcohol; polyvinyl acetate; glycerol fatty acidesters; polyacrylamide; polyacrylic acid; copolymers of ethacrylic acidor methacrylic acid (EUDRAGIT®, Rohm America, Inc., Piscataway, N.J.);poly(2-hydroxyethyl-methacrylate); polylactides; copolymers ofL-glutamic acid and ethyl-L-glutamate; degradable lacetic acid-glycolicacid copolymers; poly-D-(−)-3-hydroxybutyric acid; and other acrylicacid derivatives, such as homopolymers and copolymers ofbutylmethacrylate, methylmethacrylate, ethylmethacrylate, ethylacrylate,(2-dimethylaminoethyl)methacrylate, and(trimethylaminoethyl)methacrylate chloride.

In further embodiments, the pharmaceutical compositions are formulatedwith a non-erodible matrix device. The active ingredient(s) is dissolvedor dispersed in an inert matrix and is released primarily by diffusionthrough the inert matrix once administered. Materials suitable for useas a non-erodible matrix device included, but are not limited to,insoluble plastics, such as polyethylene, polypropylene, polyisoprene,polyisobutylene, polybutadiene, polymethylmethacrylate,polybutylmethacrylate, chlorinated polyethylene, polyvinylchloride,methyl acrylate-methyl methacrylate copolymers, ethylene-vinylacetatecopolymers, ethylene/propylene copolymers, ethylene/ethyl acrylatecopolymers, vinylchloride copolymers with vinyl acetate, vinylidenechloride, ethylene and propylene, ionomer polyethylene terephthalate,butyl rubber epichlorohydrin rubbers, ethylene/vinyl alcohol copolymer,ethylene/vinyl acetate/vinyl alcohol terpolymer, andethylene/vinyloxyethanol copolymer, polyvinyl chloride, plasticizednylon, plasticized polyethyleneterephthalate, natural rubber, siliconerubbers, polydimethylsiloxanes, silicone carbonate copolymers, and;hydrophilic polymers, such as ethyl cellulose, cellulose acetate,crospovidone, and cross-linked partially hydrolyzed polyvinyl acetate,and fatty compounds, such as carnauba wax, microcrystalline wax, andtriglycerides.

In a matrix controlled release system, the desired release kinetics canbe controlled, for example, via the polymer type employed, the polymerviscosity, the particle sizes of the polymer and/or the activeingredient(s), the ratio of the active ingredient(s) versus the polymer,and other excipients in the compositions.

The pharmaceutical compositions provided herein in a modified releasedosage form may be prepared by methods known to those skilled in theart, including direct compression, dry or wet granulation followed bycompression, melt-granulation followed by compression.

2. Osmotic Controlled Release Devices

The pharmaceutical compositions provided herein in a modified releasedosage form may be fabricated using an osmotic controlled releasedevice, including one-chamber system, two-chamber system, asymmetricmembrane technology (AMT), and extruding core system (ECS). In general,such devices have at least two components: (a) the core which containsthe active ingredient(s); and (b) a semipermeable membrane with at leastone delivery port, which encapsulates the core. The semipermeablemembrane controls the influx of water to the core from an aqueousenvironment of use so as to cause drug release by extrusion through thedelivery port(s).

In addition to the active ingredient(s), the core of the osmotic deviceoptionally includes an osmotic agent, which creates a driving force fortransport of water from the environment of use into the core of thedevice. One class of osmotic agents water-swellable hydrophilicpolymers, which are also referred to as “osmopolymers” and “hydrogels,”including, but not limited to, hydrophilic vinyl and acrylic polymers,polysaccharides such as calcium alginate, polyethylene oxide (PEO),polyethylene glycol (PEG), polypropylene glycol (PPG),poly(2-hydroxyethyl methacrylate), poly(acrylic) acid, poly(methacrylic)acid, polyvinylpyrrolidone (PVP), crosslinked PVP, polyvinyl alcohol(PVA), PVA/PVP copolymers, PVA/PVP copolymers with hydrophobic monomerssuch as methyl methacrylate and vinyl acetate, hydrophilic polyurethanescontaining large PEO blocks, sodium croscarmellose, carrageenan,hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC),hydroxypropyl methyl cellulose (HPMC), carboxymethyl cellulose (CMC) andcarboxyethyl, cellulose (CEC), sodium alginate, polycarbophil, gelatin,xanthan gum, and sodium starch glycolate.

The other class of osmotic agents are osmogens, which are capable ofimbibing water to affect an osmotic pressure gradient across the barrierof the surrounding coating. Suitable osmogens include, but are notlimited to, inorganic salts, such as magnesium sulfate, magnesiumchloride, calcium chloride, sodium chloride, lithium chloride, potassiumsulfate, potassium phosphates, sodium carbonate, sodium sulfite, lithiumsulfate, potassium chloride, and sodium sulfate; sugars, such asdextrose, fructose, glucose, inositol, lactose, maltose, mannitol,raffinose, sorbitol, sucrose, trehalose, and xylitol, organic acids,such as ascorbic acid, benzoic acid, fumaric acid, citric acid, maleicacid, sebacic acid, sorbic acid, adipic acid, edetic acid, glutamicacid, p-toluenesulfonic acid, succinic acid, and tartaric acid; urea;and mixtures thereof.

Osmotic agents of different dissolution rates may be employed toinfluence how rapidly the active ingredient(s) is initially deliveredfrom the dosage form. For example, amorphous sugars, such as MannogemeEZ (SPI Pharma, Lewes, D E) can be used to provide faster deliveryduring the first couple of hours to promptly produce the desiredtherapeutic effect, and gradually and continually release of theremaining amount to maintain the desired level of therapeutic orprophylacetic effect over an extended period of time. In this case, theactive ingredient(s) is released at such a rate to replace the amount ofthe active ingredient metabolized and excreted.

The core may also include a wide variety of other excipients andcarriers as described herein to enhance the performance of the dosageform or to promote stability or processing.

Materials useful in forming the semipermeable membrane include variousgrades of acrylics, vinyls, ethers, polyamides, polyesters, andcellulosic derivatives that are water-permeable and water-insoluble atphysiologically relevant pHs, or are susceptible to being renderedwater-insoluble by chemical alteration, such as crosslinking. Examplesof suitable polymers useful in forming the coating, include plasticized,unplasticized, and reinforced cellulose acetate (CA), cellulosediacetate, cellulose triacetate, CA propionate, cellulose nitrate,cellulose acetate butyrate (CAB), CA ethyl carbamate, CAP, CA methylcarbamate, CA succinate, cellulose acetate trimellitate (CAT), CAdimethylaminoacetate, CA ethyl carbonate, CA chloroacetate, CA ethyloxalate, CA methyl sulfonate, CA butyl sulfonate, CA p-toluenesulfonate, agar acetate, amylose triacetate, β glucan acetate, β glucantriacetate, acetaldehyde dimethyl acetate, triacetate of locust beangum, hydroxlated ethylene-vinylacetate, EC, PEG, PPG, PEG/PPGcopolymers, PVP, HEC, HPC, CMC, CMEC, HPMC, HPMCP, HPMCAS, HPMCAT,poly(acrylic) acids and esters and poly-(methacrylic) acids and estersand copolymers thereof, starch, dextran, dextrin, chitosan, collagen,gelatin, polyalkenes, polyethers, polysulfones, polyethersulfones,polystyrenes, polyvinyl halides, polyvinyl esters and ethers, naturalwaxes, and synthetic waxes.

Semipermeable membrane may also be a hydrophobic microporous membrane,wherein the pores are substantially filled with a gas and are not wettedby the aqueous medium but are permeable to water vapor, as disclosed inU.S. Pat. No. 5,798,119. Such hydrophobic but water-vapor permeablemembrane are typically composed of hydrophobic polymers such aspolyalkenes, polyethylene, polypropylene, polytetrafluoroethylene,polyacrylic acid derivatives, polyethers, polysulfones,polyethersulfones, polystyrenes, polyvinyl halides, polyvinylidenefluoride, polyvinyl esters and ethers, natural waxes, and syntheticwaxes.

The delivery port(s) on the semipermeable membrane may be formedpost-coating by mechanical or laser drilling. Delivery port(s) may alsobe formed in situ by erosion of a plug of water-soluble material or byrupture of a thinner portion of the membrane over an indentation in thecore. In addition, delivery ports may be formed during coating process,as in the case of asymmetric membrane coatings of the type disclosed inU.S. Pat. Nos. 5,612,059 and 5,698,220.

The total amount of the active ingredient(s) released and the releaserate can substantially by modulated via the thickness and porosity ofthe semipermeable membrane, the composition of the core, and the number,size, and position of the delivery ports.

The pharmaceutical compositions in an osmotic controlled-release dosageform may further comprise additional conventional excipients asdescribed herein to promote performance or processing of theformulation.

The osmotic controlled-release dosage forms can be prepared according toconventional methods and techniques known to those skilled in the art(see, Remington: The Science and Practice of Pharmacy, supra; Santus andBaker, J. Controlled Release 1995, 35, 1-21; Verma et al., DrugDevelopment and Industrial Pharmacy 2000, 26, 695-708; Verma et al., J.Controlled Release 2002, 79, 7-27).

In certain embodiments, the pharmaceutical compositions provided hereinare formulated as AMT controlled-release dosage form, which comprises anasymmetric osmotic membrane that coats a core comprising the activeingredient(s) and other pharmaceutically acceptable excipients. See,U.S. Pat. No. 5,612,059 and WO 2002/17918. The AMT controlled-releasedosage forms can be prepared according to conventional methods andtechniques known to those skilled in the art, including directcompression, dry granulation, wet granulation, and a dip-coating method.

In certain embodiments, the pharmaceutical compositions provided hereinare formulated as ESC controlled-release dosage form, which comprises anosmotic membrane that coats a core comprising the active ingredient(s),a hydroxylethyl cellulose, and other pharmaceutically acceptableexcipients.

3. Multiparticulate Controlled Release Devices

The pharmaceutical compositions provided herein in a modified releasedosage form may be fabricated a multiparticulate controlled releasedevice, which comprises a multiplicity of particles, granules, orpellets, ranging from about 10 μm to about 3 mm, about 50 μm to about2.5 mm, or from about 100 μm to about 1 mm in diameter. Suchmultiparticulates may be made by the processes know to those skilled inthe art, including wet-and dry-granulation, extrusion/spheronization,roller-compaction, melt-congealing, and by spray-coating seed cores.See, for example, Multiparticulate Oral Drug Delivery; Marcel Dekker:1994; and Pharmaceutical Pelletization Technology; Marcel Dekker: 1989.

Other excipients as described herein may be blended with thepharmaceutical compositions to aid in processing and forming themultiparticulates. The resulting particles may themselves constitute themultiparticulate device or may be coated by various film-formingmaterials, such as enteric polymers, water-swellable, and water-solublepolymers. The multiparticulates can be further processed as a capsule ora tablet.

4. Targeted Delivery

The pharmaceutical compositions provided herein may also be formulatedto be targeted to a particular tissue, receptor, or other area of thebody of the subject to be treated, including liposome-, resealederythrocyte-, and antibody-based delivery systems. Examples include, butare not limited to, U.S. Pat. Nos. 6,316,652; 6,274,552; 6,271,359;6,253,872; 6,139,865; 6,131,570; 6,120,751; 6,071,495; 6,060,082;6,048,736; 6,039,975; 6,004,534; 5,985,307; 5,972,366; 5,900,252;5,840,674; 5,759,542; and 5,709,874.

Methods of Use

Provided are methods for treating, preventing, or ameliorating one ormore symptoms of a benzodiazepine receptor mediated disease, comprisingadministering to a subject having or being suspected to have such adisease, a therapeutically effective amount of a compound of Formula 1,including a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof.

Further provided are methods of treating, preventing, or amelioratingone or more symptoms of a disease responsive to modulation of abenzodiazepine receptor, comprising administering to a subject having orbeing suspected to have such a disease, a therapeutically effectiveamount of a compound of Formula 1:

or a single enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof wherein:

R₁, R₃, R₄, R₅, R₆, R₈, R₉, R₁₀, and R₁₁ are independently selected fromthe group consisting of hydrogen and deuterium;

R₂, R₇, R₁₂, and R₁₃ are independently selected from the groupconsisting of —CH₃, —CH₂D, —CHD₂, and —CD₃;

provided that said compound of Formula 1 contains at least one deuteriumatom; and

provided that deuterium enrichment in said compound of Formula 1 is atleast about 1%.

Further provided are methods of treating, preventing, or amelioratingone or more symptoms of a disease responsive to modulation of abenzodiazepine receptor, comprising administering to a subject having orbeing suspected to have such a disease, a therapeutically effectiveamount of a compound of Formula 1, including a single enantiomer, amixture of the (+)-enantiomer and the (−)-enantiomer, a mixture of about90% or more by weight of the (−)-enantiomer and about 10% or less byweight of the (+)-enantiomer, a mixture of about 90% or more by weightof the (+)-enantiomer and about 10% or less by weight of the(−)-enantiomer, an individual diastereomer, or a mixture ofdiastereomers thereof; or a pharmaceutically acceptable salt, solvate,or prodrug thereof.

Furthermore, provided herein are methods of modulating the activity of abenzodiazepine receptor, comprising contacting the receptor with atleast one compound of Formula 1, including a single enantiomer, amixture of the (+)-enantiomer and the (−)-enantiomer, a mixture of about90% or more by weight of the (−)-enantiomer and about 10% or less byweight of the (+)-enantiomer, a mixture of about 90% or more by weightof the (+)-enantiomer and about 10% or less by weight of the(−)-enantiomer, an individual diastereomer, or a mixture ofdiastereomers thereof; or a pharmaceutically acceptable salt, solvate,or prodrug thereof. In one embodiment, the benzodiazepine receptor isexpressed by a cell.

Provided herein are methods for treating a subject, including a human,having or suspected of having a disease or disorder involving sleep suchas by way of example only, sleep related disorders, insomnia,narcolepsy, parasomnias, restless leg syndrome, sleep apnea, REM sleepbehavior disorder, obstructive sleep apnea, hypersomnia, delayed sleepphase syndrome, advanced sleep phase syndrome, non-24-hour sleep-wakesyndrome, sleep terror, somnambulism, sleep sickness, and dysomnias orfor preventing such a disease or disorder in a subject prone to thedisease; and/or for providing a human with a hypnotic, anxiolytic oranti-convulsive effect, comprising administering to the subject atherapeutically effective amount of a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; so as to affect decreasedinter-individual variation in plasma levels of the compound or ametabolite thereof, during the treatment of the disease as compared tothe corresponding non-isotopically enriched compound.

In certain embodiments, the inter-individual variation in plasma levelsof the compounds of Formula 1, or metabolites thereof, is decreased bygreater than about 5%, greater than about 10%, greater than about 20%,greater than about 30%, greater than about 40%, or by greater than about50% as compared to the corresponding non-isotopically enriched compound.

Provided herein are methods for treating a subject, including a human,having or suspected of having a or disorder involving sleep such as byway of example only, sleep related disorders, insomnia, narcolepsy,parasomnias, restless leg syndrome, sleep apnea, REM sleep behaviordisorder, obstructive sleep apnea, hypersomnia, delayed sleep phasesyndrome, advanced sleep phase syndrome, non-24-hour sleep-wakesyndrome, sleep terror, somnambulism, sleep sickness, and dysomnias orfor preventing such a disease or disorder in a subject prone to thedisease; and/or for providing a human with a hypnotic, anxiolytic oranti-convulsive effect, comprising administering to the subject atherapeutically effective amount of a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; so as to affect increased averageplasma levels of the compound or decreased average plasma levels of atleast one metabolite of the compound per dosage unit as compared to thecorresponding non-isotopically enriched compound.

In certain embodiments, the average plasma levels of the compound ofFormula 1 are increased by greater than about 5%, greater than about10%, greater than about 20%, greater than about 30%, greater than about40%, or greater than about 50% as compared to the correspondingnon-isotopically enriched compounds.

In certain embodiments, the average plasma levels of a metabolite of thecompound of Formula 1 are decreased by greater than about 5%, greaterthan about 10%, greater than about 20%, greater than about 30%, greaterthan about 40%, or greater than about 50% as compared to thecorresponding non-isotopically enriched compounds

Plasma levels of the compound of Formula 1, or metabolites thereof, aremeasured using the methods described by Li et al. (Rapid Communicationsin Mass Spectrometry 2005, 19, 1943-1950).

Provided herein are methods for treating a subject, including a human,having or suspected of having a disease or disorder involving sleep suchas by way of example only, sleep related disorders, insomnia,narcolepsy, parasomnias, restless leg syndrome, sleep apnea, REM sleepbehavior disorder, obstructive sleep apnea, hypersomnia, delayed sleepphase syndrome, advanced sleep phase syndrome, non-24-hour sleep-wakesyndrome, sleep terror, somnambulism, sleep sickness, and dysomnias orfor preventing such a disease or disorder in a subject prone to thedisease; and/or for providing a human with a hypnotic, anxiolytic oranti-convulsive effect, comprising administering to the subject atherapeutically effective amount of a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; so as to affect a decreasedinhibition of, and/or metabolism by at least one cytochrome P₄₅₀ isoformin the subject during the treatment of the disease as compared to thecorresponding non-isotopically enriched compound.

Examples of cytochrome P₄₅₀ isoforms in a mammalian subject include, butare not limited to, CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2A13, CYP2B6,CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP2G1, CYP2J2,CYP2R1, CYP2S1, CYP3A4, CYP3A5, CYP3A5P1, CYP3A5P2, CYP3A7, CYP4A11,CYP4B1, CYP4F2, CYP4F3, CYP4F8, CYP4F11, CYP4F12, CYP4X1, CYP4Z1,CYP5A1, CYP7A1, CYP7B1, CYP8A1, CYP8B1, CYP11A1, CYP11B1, CYP11B2,CYP17, CYP19, CYP21, CYP24, CYP26A1, CYP26B1, CYP27A1, CYP27B1, CYP39,CYP46, and CYP51.

In certain embodiments, the decrease in inhibition of the cytochromeP₄₅₀ isoform by a compound of Formula 1 is greater than about 5%,greater than about 10%, greater than about 20%, greater than about 30%,greater than about 40%, or greater than about 50% as compared to thecorresponding non-isotopically enriched compounds.

The inhibition of the cytochrome P₄₅₀ isoform is measured by the methodof Ko et al. (British Journal of Clinical Pharmacology, 2000, 49,343-351).

Provided herein are methods for treating a subject, including a human,having or suspected of having a disease or disorder involving sleep suchas by way of example only, sleep related disorders, insomnia,narcolepsy, parasomnias, restless leg syndrome, sleep apnea, REM sleepbehavior disorder, obstructive sleep apnea, hypersonmia, delayed sleepphase syndrome, advanced sleep phase syndrome, non-24-hour sleep-wakesyndrome, sleep terror, somnambulism, sleep sickness, and dysonmias orfor preventing such a disease or disorder in a subject prone to thedisease; and/or for providing a human with a hypnotic, anxiolytic oranti-convulsive effect, comprising administering to the subject atherapeutically effective amount of a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; so as to affect a decreasedmetabolism via at least one polymorphically-expressed cytochrome P₄₅₀isoform in the subject during the treatment of the disease as comparedto the corresponding non-isotopically enriched compound.

Examples of polymorphically-expressed cytochrome P₄₅₀ isoforms in amammalian subject include, but are not limited to, CYP2C8, CYP2C9,CYP2C19, and CYP2D6.

In certain embodiments, the decrease in metabolism of the compound ofFormula 1 by at least one polymorphically-expressed cytochrome P₄₅₀isoforms cytochrome P₄₅₀ isoform is greater than about 5%, greater thanabout 10%, greater than about 20%, greater than about 30%, greater thanabout 40%, or greater than about 50% as compared to the correspondingnon-isotopically enriched compound.

The metabolic activities of the cytochrome P₄₅₀ isoforms are measured bythe method described in Example 22.

Provided herein are methods for treating a subject, including a human,having or suspected of having a disease or disorder involving sleep suchas by way of example only, sleep related disorders, insomnia,narcolepsy, parasomnias, restless leg syndrome, sleep apnea, REM sleepbehavior disorder, obstructive sleep apnea, hypersomnia, delayed sleepphase syndrome, advanced sleep phase syndrome, non-24-hour sleep-wakesyndrome, sleep terror, somnambulism, sleep sickness, and dysomnias orfor preventing such a disease or disorder in a subject prone to thedisease; and/or for providing a human with a hypnotic, anxiolytic oranti-convulsive effect, comprising administering to the subject atherapeutically effective amount of a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; so as to affect at least onestatistically-significantly improved disease-control and/ordisease-eradication endpoint, as compared to the correspondingnon-isotopically enriched compound.

An example of an improved disease-control and/or disease-eradicationendpoint includes but is not limited to, statistically significantimprovement of sleep indices as compared to the correspondingnon-isotopically enriched compound.

In another aspect, are provided methods for treating a mammaliansubject, particularly a human having, suspected of having, or beingprone to a disease or condition involving a benzodiazepine receptor,comprising administering to a mammalian subject in need thereof atherapeutically effective amount of a benzodiazepine receptor modulatorcomprising at least one of the compounds of Formula 1, the(−)-enantiomer of one of the compounds of Formula 1, the (+)-enantiomerof one of the compounds of Formula 1, or a pharmaceutically acceptablesalt, solvate, or prodrug thereof, so as to affect increased averageplasma levels of said compound or decreased average plasma levels of atleast one metabolite of said compound per dosage unit as compared to thenon-isotopically enriched compound.

Provided herein are methods for treating a subject, including a human,having or suspected of having a disease or disorder involving sleep suchas by way of example only, sleep related disorders, insomnia,narcolepsy, parasomnias, restless leg syndrome, sleep apnea, REM sleepbehavior disorder, obstructive sleep apnea, hypersomnia, delayed sleepphase syndrome, advanced sleep phase syndrome, non-24-hour sleep-wakesyndrome, sleep terror, somnambulism, sleep sickness, and dysomnias orfor preventing such a disease or disorder in a subject prone to thedisease; and/or for providing a human with a hypnotic, anxiolytic oranti-convulsive effect, comprising administering to the subject atherapeutically effective amount of a compound of Formula 1, including asingle enantiomer, a mixture of the (+)-enantiomer and the(−)-enantiomer, a mixture of about 90% or more by weight of the(−)-enantiomer and about 10% or less by weight of the (+)-enantiomer, amixture of about 90% or more by weight of the (+)-enantiomer and about10% or less by weight of the (−)-enantiomer, an individual diastereomer,or a mixture of diastereomers thereof; or a pharmaceutically acceptablesalt, solvate, or prodrug thereof; so as to affect an improved clinicaleffect as compared to the corresponding non-isotopically enrichedcompound. Examples of improved clinical effects include, but are notlimited to, statistically-significant improvement of sleep indices, morerapid symptomatic relief from sleep disburtances, and improved moodpatterns, as compared to the corresponding non-isotopically enrichedcompound.

Depending on the disease to be treated and the subject's condition, thecompound of Formula 1 provided herein may be administered by oral,parenteral (e.g., intramuscular, intraperitoneal, intravenous, ICV,intracisternal injection or infusion, subcutaneous injection, orimplant), inhalation, nasal, vaginal, rectal, sublingual, or topical(e.g., transdermal or local) routes of administration, and may beformulated, alone or together, in suitable dosage unit withpharmaceutically acceptable carriers, adjuvants and vehicles appropriatefor each route of administration.

The dose may be in the form of one, two, three, four, five, six, or moresub-doses that are administered at appropriate intervals per day. Thedose or sub-doses can be administered in the form of dosage unitscontaining from about 0.1 to about 1000 milligram, from about 0.1 toabout 500 milligrams, or from 0.5 about to about 100 milligram activeingredient(s) per dosage unit, and if the condition of the patientrequires, the dose can, by way of alternative, be administered as acontinuous infusion.

In certain embodiments, an appropriate dosage level is about 0.01 toabout 100 mg per kg patient body weight per day (mg/kg per day), about0.01 to about 50 mg/kg per day, about 0.01 to about 25 mg/kg per day, orabout 0.05 to about 10 mg/kg per day, which may be administered insingle or multiple doses. A suitable dosage level may be about 0.01 toabout 100 mg/kg per day, about 0.05 to about 50 mg/kg per day, or about0.1 to about 10 mg/kg per day. Within this range the dosage may be about0.01 to about 0.1, about 0.1 to about 1.0, about 1.0 to about 1.0, orabout 10 to about 50 mg/kg per day.

In another embodiment, are provided methods for treating a mammualiansubject, particularly a human having, suspected of having, or beingprone to a disease or condition involving a benzodiazepine receptor,comprising administering to a mammalian subject in need thereof atherapeutically effective amount of a benzodiazepine receptor modulatorcomprising at least one of the compounds of Formula 1, the(−)-enantiomer of one of the compounds of Formula 1, the (+)-enantiomerof one of the compounds of Formula 1, or a pharmaceutically acceptablesalt, solvate, or prodrug thereof, so as to affect improvedneurotransmitter levels as compared to the non-isotopically enrichedcompound.

In some embodiments, neurotransmitter levels are increased by greaterthan about 5%. In other embodiments, neurotransmitter levels areincreased by greater than about 10%. In other embodiments,neurotransmitter levels are increased by greater than about 20%. Inother embodiments, neurotransmitter levels are increased by greater thanabout 30%. In other embodiments, neurotransmitter levels are increasedby greater than about 40%. In other embodiments, neurotransmitter levelsare increased by greater than about 50%.

Neurotransmitter levels are measured by the methods of Li, (RapidCommunications in Mass Spectrometry, 2005, 19(14), 1943-50).

In some embodiments, the disease or condition involving a benzodiazepinereceptor is selected from the group consisting of a sleep disorderand/or a disease in which a hypnotic, an anxiolytic or ananti-convulsive effect is beneficial.

In some embodiments, the method for treating a mammalian subject,particularly a human having, suspected of having, or being prone to adisease or condition involving a benzodiazepine receptor, comprisingadministering to a mammalian subject in need thereof a therapeuticallyeffective amount of a benzodiazepine receptor modulator comprising acompound of Formula 1, wherein said compound of Formula 1 represents amixture of the (+)-enantiomer and the (−)-enantiomer, or wherein saidcompound of Formula 1 contains about 90% or more by weight of the(−)-enantiomer of said compound and about 10% or less by weight of the(+)-enantiomer of said compound, or wherein said compound of Formula 1contains about 90% or more by weight of the (+)-enantiomer of saidcompound and about 10% or less by weight of the (−)-enantiomer of saidcompound; provided that said compound of Formula 1 contains at least onedeuterium atom; and provided that deuterium enrichment in said compoundof Formula 1 is at least about 1%.

Combination Therapy

The compounds provided herein may also be combined or used incombination with other agents useful in the treatment, prevention, oramelioration of one or more symptoms of the diseases or conditions forwhich the compound provided herein are useful, sleep related disorders,insomnia, narcolepsy, parasomnias, restless leg syndrome, sleep apnea,REM sleep behavior disorder, obstructive sleep apnea, hypersonmia,delayed sleep phase syndrome, advanced sleep phase syndrome, non-24-hoursleep-wake syndrome, sleep terror, somnambulism, sleep sickness, anddysomnias. Or, by way of example only, the therapeutic effectiveness ofone of the compounds described herein may be enhanced by administrationof an adjuvant (i.e., by itself the adjuvant may only have minimaltherapeutic benefit, but in combination with another therapeutic agent,the overall therapeutic benefit to the patient is enhanced).

Such other agents, adjuvants, or drugs, may be administered, by a routeand in an amount commonly used therefor, simultaneously or sequentiallywith a compound of Formula 1. When a compound of Formula 1 providedherein is used contemporaneously with one or more other drugs, apharmaceutical composition containing such other drugs in addition tothe compound provided herein may be utilized, but is not required.Accordingly, the pharmaceutical compositions provided herein includethose that also contain one or more other active ingredients ortherapeutic agents, in addition to the compound provided herein.

In certain embodiments, the compounds provided herein can be combinedwith one or more modulators of GABA_(A) receptors known in the art,including, but not limited to, imidazolpyridines, pyrazolopyrimidines,such as by way of example only, zaleplon, cyclopyrrones, by way ofexample only, eszopiclone, zopiclone, chlordiazepoxide, diazepam,nitrazepam, and flurazepam.

In certain embodiments, the compounds provided herein can be combinedwith one or more natural, semisynthetic, or fully synthetic opioidsknown in the art, including, but not limited to, morphine, codeine,thebain, diacetylmorphine, oxycodone, hydrocodone, hydromorphone,oxymorphone, nicomorphine, fentanyl, α-methylfentanyl, alfentanil,sufentanil, remifentanyl, carfentanyl, ohmefentanyl, pethidine,ketobemidone, propoxyphene, dextropropoxyphene, methadone, loperamide,pentazocine, buprenorphine, etorphine, butorphanol, nalbufine,levorphanol, naloxone, naltrexone, and tramadol.

In certain embodiments, the compounds provided herein can be combinedwith one or more local and/or general anesthetics and sedatives known inthe art, including, but not limited to, propofol, procaine, lidocaine,prilocalne, bupivicaine, levobupivicaine, nitrous oxide, halothane,enflurane, isoflurane, sevoflurane, desflurane, thiopental,methohexital, etomidate, diazepam, midazolam, lorazepam,succinylcholine, vecuronium, rocuronium, pipecuronium, rapacuronium,tubocurarine, and gallamine.

The compounds provided herein can also be administered in combinationwith other classes of compounds, including, but not limited to,endothelin converting enzyme (ECE) inhibitors, such as phosphoramidon;thromboxane receptor antagonists, such as ifetroban; potassium channelopeners; thrombin inhibitors, such as hirudin; growth factor inhibitors,such as modulators of PDGF activity; platelet activating factor (PAF)antagonists; anti-platelet agents, such as GPIIb/IIIa blockers (e.g.,abdximab, eptifibatide, and tirofiban), P2Y(AC) antagonists (e.g.,clopidogrel, ticlopidine and CS-747), and aspirin; anticoagulants, suchas warfarin; low molecular weight heparins, such as enoxaparin; FactorVIIa Inhibitors and Factor Xa Inhibitors; renin inhibitors; neutralendopeptidase (NEP) inhibitors; vasopepsidase inhibitors (dual NEP-ACEinhibitors), such as omapatrilat and gemopatrilat; HMG CoA reductaseinhibitors, such as pravastatin, lovastatin, atorvastatin, simvastatin,NK-104 (a.k.a. itavastatin, nisvastatin, or nisbastatin), and ZD-4522(also known as rosuvastatin, or atavastatin or visastatin); squalenesynthetase inhibitors; fibrates; bile acid sequestrants, such asquestran; niacin; anti-atherosclerotic agents, such as ACAT inhibitors;MTP Inhibitors; calcium channel blockers, such as amlodipine besylate;potassium channel activators; alpha-adrenergic agents; β-adrenergicagents, such as carvedilol and metoprolol; antiarrhythmic agents;diuretics, such as chlorothlazide, hydrochlorothiazide, flumethiazide,hydroflumethiazide, bendroflumethiazide, methylchlorothiazide,trichloromethiazide, polythiazide, benzothlazide, ethacrynic acid,tricrynafen, chlorthalidone, furosenilde, musolimine, bumetamide,triamterene, amiloride, and spironolactone; thrombolytic agents, such astissue plasminogen activator (tPA), recombinant tPA, streptokinase,urokinase, prourokinase, and anisoylated plasminogen streptokinaseactivator complex (APSAC); anti-diabetic agents, such as biguamides(e.g. metformin), glucosidase inhibitors (e.g., acarbose), insulins,meglitinides (e.g., repaglinide), sulfonylureas (e.g., glimepiride,glyburide, and glipizide), thiozolidinediones (e.g. troglitazone,rosiglitazone and pioglitazone), and PPAR-gamma agonists;mineralocorticoid receptor antagonists, such as spironolactone andeplerenone; growth hormone secretagogues; aP2 inhibitors;phosphodiesterase inhibitors, such as PDE III inhibitors (e.g.,cilostazol) and PDE V inhibitors (e.g., sildenafil, tadalafil,vardenafil); protein tyrosine kinase inhibitors; antiinflammatories;antiproliferatives, such as methotrexate, FK506 (tacrolimus, Prograf),mycophenolate mofetil; chemotherapeutic agents; immunosuppressants;anticancer agents and cytotoxic agents (e.g., alkylating agents, such asnitrogen mustards, alkyl sulfonates, nitrosoureas, ethylenimines, andtriazenes); antimetabolites, such as folate antagonists, purineanalogues, and pyrridine analogues; antibiotics, such as anthracyclines,bleomycins, mitomycin, dactinomycin, and plicamycin; enzymes, such asL-asparaginase; farnesyl-protein transferase inhibitors; hormonalagents, such as glucocorticoids (e.g., cortisone),estrogens/antiestrogens, androgens/antiandrogens, progestins, andluteinizing hormone-releasing hormone anatagonists, and octreotideacetate; microtubule-disruptor agents, such as ecteinascidins;microtubule-stabilizing agents, such as pacitaxel, docetaxel, andepothilones A-F; plant-derived products, such as vinca alkaloids,epipodophyllotoxins, and taxanes; and topoisomerase inhibitors;prenyl-protein transferase inhibitors; and cyclosporins; steroids, suchas prednisone and dexamethasone; cytotoxic drugs, such as azathiprineand cyclophosphamide; TNF-alpha inhibitors, such as tenidap; anti-TNFantibodies or soluble TNF receptor, such as etanercept, rapamycin, andleflunimide; and cyclooxygenase-2 (COX-2) selective inhibitors, such ascelecoxib and rofecoxib; and miscellaneous agents such as, hydroxyurea,procarbazine, mitotane, hexamethylmelamine, gold compounds, platinumcoordination complexes, such as cisplatin, satraplatin, and carboplatin.

Kits/Articles of Manufacture

For use in the therapeutic applications described herein, kits andarticles of manufacture are also described herein. Such kits cancomprise a carrier, package, or container that is compartmentalized toreceive one or more containers such as vials, tubes, and the like, eachof the container(s) comprising one of the separate elements to be usedin a method described herein. Suitable containers include, for example,bottles, vials, syringes, and test tubes. The containers can be formedfrom a variety of materials such as glass or plastic.

For example, the container(s) can comprise one or more compoundsdescribed herein, optionally in a composition or in combination withanother agent as disclosed herein. The container(s) optionally have asterile access port (for example the container can be an intravenoussolution bag or a vial having a stopper pierceable by a hypodermicinjection needle). Such kits optionally comprise a compound with anidentifying description or label or instructions relating to its use inthe methods described herein.

A kit will typically comprise one or more additional containers, eachwith one or more of various materials (such as reagents, optionally inconcentrated form, and/or devices) desirable from a commercial and userstandpoint for use of a compound described herein. Non-limiting examplesof such materials include, but are not limited to, buffers, diluents,filters, needles, syringes; carrier, package, container, vial and/ortube labels listing contents and/or instructions for use, and packageinserts with instructions for use. A set of instructions will alsotypically be included.

A label can be on or associated with the container. A label can be on acontainer when letters, numbers or other characters forming the labelare attached, molded or etched into the container itself; a label can beassociated with a container when it is present within a receptacle orcarrier that also holds the container, e.g., as a package insert. Alabel can be used to indicate that the contents are to be used for aspecific therapeutic application. The label can also indicate directionsfor use of the contents, such as in the methods described herein. Theseother therapeutic agents may be used, for example, in the amountsindicated in the Physicians' Desk Reference (PDR) or as otherwisedetermined by one of ordinary skill in the art.

EXAMPLES

For all of the following examples, standard work-up and purificationmethods known to those skilled in the art can be utilized. Syntheticmethodologies illustrated in Scheme 1 is intended to exemplify theapplicable chemistry through the use of specific examples and are notindicative of the scope of what is claimed herein.

Example 1 1-p-tolyl-ethanone

Anhydrous aluminum chloride (89.6 g, 0.67 mol) was added to a solutionof toluene (28.5 g, 0.3 μmol) in 120 mL of dry carbon disulfide. Themixture was heated to reflux and acetic anhydride (24.5 g, 0.24 mol) wasadded over one hour. Heating was continued for an additional hour. Thesolvent was removed by distillation. The reaction mixture was cooled andslowly poured into a well-stirred mixture of ice and hydrochloric acid.The mixture was extracted several times with ether. The combinedextracts were washed with water and 10% sodium hydroxide, dried overcalcium chloride, filtered, and the solvent was removed. Distillationgave the desired product 1-p-tolyl-ethanone (27.08 g). ¹H NMR (300 MHz,DMSO-d₆) δ 2.36 (s, 3H), 2.50 (s, 3H), 7.32 (d, 2H), 7.85 (d, 2H); EI-MS(M⁺): 134.

Example 2 2-Bromo-1-p-tolyl-1-ethanone

To a solution of 1-p-tolyl-ethanone (0.5 g, 4.16 mmol) indichloromethane-methanol (50 ml-20 mL) was added tetrabutylammoniumtribromide (2.2 g, 4.58 mmol) at room temperature. The mixture wasstirred until the orange color faded. The solvent was then distilledunder reduced pressure and the resulting precipitate was extracted withethyl acetate. The organic layer was dried over sodium sulfate andevaporated in vacuo to give a residue which was purified by flash columnchromatography to yield the desired product 2-bromo-1-p-tolyl-1-ethanone(0.74 g, 84%). ¹H NMR (300 MHz, DMSO-d₆) δ 2.39 (s, 3H), 4.89 (s, 2H),7.37 (d, 2H), 7.89 (d, 2H); ESI-MS (MH⁺): 213 and 215.

Example 3 6-Methyl-2-p-tolyl-imidazo[1,2-a]pyridine

A solution of 2-bromo-1-p-tolyl-ethanone (500 mg, 2.3 mmol) indimethylformamide (2 mL) was added slowly to a solution of5-methyl-pyridin-2-yl-amine (249 mg, 2.3 mmol) in dimethylformamide (2mL). NaHCO₃ (386 mg, 4.6 mmol) was added in portions and the mixture wasstirred at room temperature for 15 minutes, then at reflux for 1.5hours. The mixture was cooled and poured into water (5 mL). The solidwas collected, washed with water (2 mL) and recrystallized fromdimethylformamide (5 mL) to yield the desired product6-methyl-2-p-tolyl-imidazo[1,2-a]pyridine (360 mg, 70%). ¹H NMR (300MHz, DMSO-d₆) δ 2.27 (s, 3H), 2.32 (s, 3H), 7.08 (d, 1H), 7.21 (d, 2H),7.46 (d, 1H), 7.83 (d, 2H), 8.24 (s, 1H), 8.29 (s, 1H); ESI-MS (MH⁺),223.

Example 4 d₁₄-6-Methyl-2-p-tolyl-imidazo[1,2-a]pyridine

A mixture of 6-methyl-2-p-tolyl-imidazo[1,2-a]pyridine (2 g, 9 mmol),10% Pd/C (20% weight, 0.4 g), sodium formate (306 mg, 4.5 mmol), D₂O anddioxane (20 ml, D₂O/dioxane, 8/1, v/v) was degassed by bubbling a steamof nitrogen into the mixture for 2 minutes. The reaction was heated to160° C. for 30 hours. The reaction was cooled, extracted with methanol,dried, concentrated and purified by flash column chromatography and theprocess was repeated again to yield the desired productd₁₄-6-methyl-2-p-tolyl-imidazo[1,2-a]pyridine (450 mg, 21% yield). Thepercent incorporation of deuterium was determined by NMR. ESI-MS (MH⁺)237.

Example 5d₁₃-2-Hydroxy-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-a]pyridin-3-yl)-acetamide

N,N-Dimethyl-2-oxo-acetamide hemihydrate (523 mg) was added to asolution of d₁₄-6-methyl-2-p-tolyl-imidazo[1,2-a]pyridine (450 mg, 2mmol) in 4-methyl-2-pentanone (10 mL) at 60° C. and stirred for 3 hours.The temperature was increased to 80° C. and stirring was maintained foran additional 12 hours. The reaction was cooled and the solvent wasremoved under reduced pressure. The residue was purified by flash columnchromatography to yield the desired productd₁₃-2-hydroxy-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-a]pyridin-3-yl)-acetamide(400 mg, 60%). ¹H NMR (300 MHz, CDCl₃) δ 7.68 (s, 0.24H), 7.28 (s,0.30H), 5.73 (s, 1H), 4.92 (br, 1H), 2.87 (s, 3H), 2.36 (s, 3H); ESI-MS(MH)⁺337.

Example 6d₁₃-N,N-dimethyl-2-(6-methyl-2-p-totyl-imidazo[1,2-α]pyridine-3-yl)-acetamide(d₁₃-ambien)

Phosphorus tribromide was added to a solution ofd₁₃-2-hydroxy-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-a]pyridin-3-yl)-acetamide(400 mg, 1.19 mmol) in tetrahydrofuran at 40° C. A white precipitateformed immediately. The mixture was heated at reflux until completion.The mixture was added to a saturated aqueous solution of NaHCO₃ (50 mL)and extracted with ethyl acetate. The combined organic layers were driedover sodium sulfate, filtered and concentrated to yield the desiredproductd₁₃-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-α]pyridine-3-yl)-acetamide(150 mg, 38%). ¹H NMR (300 MHz, CDCl₃) δ 7.56 (s, 0.27H), 4.11 (s, 2H),2.96 (s, 3H), 2.90 (s, 3H); ESI-MS (MH+): 321.

Example 7 d₆-5-Methyl-pyridin-2-yl-amine

A mixture of 5-methyl-pyridin-2-yl-amine (1 g, 9.2 mmol), 10% Pd/C (20%weight, 0.2 g), sodium formate (312 mg, 4.6 mmol), D₂O and dioxane (34ml, D₂O/dioxane, 8/1, v/v) was degassed by bubbling a steam of nitrogeninto the mixture for 2 minutes. The reaction was heated to 180° C. for24 hours. The reaction was cooled, filtered, washed with methanol,concentrated and purified by flash column chromatography to give thedesired product d₆-5-methyl-pyridin-2-yl-amine (661 mg, 58%). ¹H NMR(300 MHz, D₂O) δ 3.18 (s); ESI-MS (MH⁺): 115.

Example 8 d₆-6-Methyl-2-p-tolyl-imidazo[1,2-a]pyridine

Prepared according to Example 3 by substitutingd₆-5-methyl-pyridin-2-yl-amine for 5-methyl-pyridin-2-yl-amine. ¹H NMR(300 MHz, CDCl₃) δ 2.38 (s, 3H), 7.24 (d, 2H), 7.74 (s, 1H), 7.83 (d,2H); ESI-MS (MH⁺): 229.

Example 9d₆-2-Hydroxy-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-a]pyridin-3-yl)-acetamide

Prepared according to Example 5. ¹H NMR (300 MHz, CDCl₃) δ 7.68 (s, 2H),7.28 (s, 2H), 5.72 (s, 1H), 4.85 (br, 1H), 2.87 (s, 3H), 2.46 (s, 3H),2.36 (s, 3H); ESI-MS (MH⁺): 330.

Example 10

d₆-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-α]pyridine-3-yl)-acetamide(d₆-ambien)

Prepared according to Example 6. ¹H NMR (300 MHz, CDCl₃) δ 7.56 (s, 2H),7.27 (s, 2H), 4.11 (s, 2H), 2.96 (s, 3H), 2.89 (s, 3H), 2.41 (s, 3H);ESI-MS (MH⁺): 314.

Example 11 d₃-1-p-tolyl-ethanone

Prepared according to Example 1 by substituting d₃-toluene for toluene,¹H NMR (300 MHz, CDCl₃): δ 7.88 (d, J=8.1 Hz, 2H), 7.27 (d, J=8.1 Hz,2H), 2.60 (s, 3H); EI-MS m/z=137 (radical cation)

Example 12 d₃-2-Bromo-1-p-tolyl-1-ethanone

Prepared according to Example 2, ¹H NMR (300 MHz, CDCl₃): δ 7.89 (d,J=7.8 Hz, 2H), 7.28 (d, J=7.8 Hz, 2H), 4.44 (s, 2H);

Example 13 d₃-6-Methyl-2-p-tolyl-imidazo[1,2-a]pyridine

Prepared according to Example 3, ¹H NMR (300 MHz, CDCl₃) δ 7.86 (m, 3H),7.74 (s, 1H), 7.53 (d, J=9.0 Hz, 2H), 7.25 (d, J=7.8 Hz, 2H), 7.01 (d,J=9.0 Hz, 1H), 2.34 (s, 3H); ESI-MS m/z=226 (MH⁺)

Example 14d₃-2-Hydroxy-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-a]pyridin-3-yl)-acetamide

Prepared according to Example 5, ¹H NMR (300 MHz, CDCl₃) δ 7.98 (s, 1H),7.68 (d, J=8.1 Hz, 2H), 7.59 (d, J=9.0 Hz, 1H), 7.27 (d, J=8.1 Hz, 2H),7.11 (d, J=9.0 Hz, 1H), 5.72 (s, 1H), 2.96 (s, 3H), 2.39 (s, 3H), 2.34(s, 3H); ESI-MS m/z=327 (MH⁺).

Example 15d₃-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-α]pyridine-3-yl)-acetamide(d₃-ambien)

Prepared according to Example 6, ¹H NMR (300 MHz, CDCl₃) δ 8.02 (s, 1H),7.55 (m, 3H), 7.26 (d, J=8.1 Hz, 2H), 7.05 (d, J=9.0 Hz, 1H), 4.11 (s,2H), 2.96 (s, 3H), 2.89 (s, 3H), 2.36 (s, 3H); ESI-MS m/z=311 (MH+)

Example 16 d₆-2,3-Dihydroxy-N,N,N′N′-tetramethylsuccinamide

The procedure is carried out according to Seebach et al. OrganicSyntheses 1990, Coll. Vol 7, 41. Into a mixture of 618 g (3 mol) ofdiethyl tartrate and 600 mL of freshly distilled methanol in a 2-LErlenmeyer flask is poured at least 450 mL (7 mol) of liquid, anhydrous,cold (−78° C.) d₆-dimethylamine. The mixture is swirled briefly and thenallowed to stand in a hood for 3 days with a drying tube in place. Afterseeding and cooling in a refrigerator overnight, the massive crystalsare collected by suction filtration. The filtrate is concentrated,seeded, and cooled to yield a second crop. The combined crystals arewashed with cold methanol (−30° C.) and dried under reduced pressure at70-100° C. (oil bath) to give the desired product,d₆-2,3-dihydroxy-N,N,N′,N′-tetramethylsuccinamide.

Example 17 d₆-N,N-Dimethyl glyoxamide

The procedure is carried out according to Trova et al. Bioorg. Med.Chem. 2003, 11(13), 2695-2708. A solution ofd₆-2,3-dihydroxy-N,N,N′,N′-tetramethylsuccinamide (9.79 mmol) indichloromethane (60 mL) is magnetically stirred at 0° C., under drynitrogen, as periodic acid dihydrate (12.2 mmol) is added. The resultingsolution is stirred for 4.5 hours, decanted from the solid precipitate,dried over sodium sulfate, filtered, and the solvent is evaporated underreduced pressure to provide the desired product, d₆-N,N-dimethylglyoxamide, as an oil.

Example 18d₁₉-2-Hydroxy-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-a]pyridin-3-yl)-acetamide

The title compound is prepared according to Example 5 by substitutingd₆-N,N-dimethyl glyoxamide for N,N-dimethyl glyoxamide.

Example 19d₁₉-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-α]pyridine-3-yl)-acetamide(d₁₉-ambien)

The title compound is prepared according to Example 6.

Example 20d₂₁-N,N-dimethyl-2-(6-methyl-2-p-tolyl-imidazo[1,2-α]pyridine-3-yl)-acetamide(d₂₁-ambien)

d₁₉-Ambien (0.014 mmol) is taken up in 0.5 ml of d₄-methanol and addeddropwise to a 0.1M solution of sodium carbonate in D₂O (pH=11.4) atambient temperature; the solution is stirred for 4 days, diluted withdichloromethane, washed with brine and dried over anhydrous magnesiumsulfate. The solvent is removed under reduced pressure to yield thedesired product, d₂₁-ambien.

Example 21 In vitro Liver Microsomal Stability Assay

Liver microsomal stability assays were conducted at 1 mg per mL livermicrosome protein with an NADPH-generating system in 2% NaHCO₃ (2.2 mMNADPH, 25.6 mM glucose 6-phosphate, 6 units per mL glucose 6-phosphatedehydrogenase and 3.3 mM MgCl₂). Test compounds were prepared assolutions in 20% acetonitrile-water and added to the assay mixture(final assay concentration 5 microgram per mL) and incubated at 37° C.Final concentration of acetonitrile in the assay were <1%. Aliquots (50μL) were taken out at times 0, 15, 30, 45, and 60 minutes, and dilutedwith ice cold acetonitrile (200 μL) to stop the reactions. Samples werecentrifuged at 12000 RPM for 10 minutes to precipitate proteins.Supernatants were transferred to microcentrifuge tubes and stored forLC/MS/MS analysis of the degradation half-life of the test compounds. Ithas thus been found that the compounds of formula (I) according to thepresent invention that have been tested in this assay showed an increaseof 10% or more in the degradation half-life, as compared to thenon-isotopically enriched drug. For example, the degradation half-lifeof d₃-ambien (Example 15), d₆-ambien (Example 10) and d₁₃-ambien(Example 6) were increased by 15-66% as compared to non-isotopicallyenriched ambien.

Example 22 In vitro Metabolism Using Human Cytochrome P₄₅₀ enzymes

The cytochrome P₄₅₀ enzymes are expressed from the corresponding humancDNA using a baculovirus expression system (BD Biosciences). A 0.25milliliter reaction mixture containing 0.8 milligrams per milliliterprotein, 1.3 millimolar NADP⁺, 3.3 millimolar glucose-6-phosphate, 0.4U/mL glucose-6-phosphate dehydrogenase, 3.3 millimolar magnesiumchloride and 0.2 millimolar of a compound of Formula 1, thecorresponding non-isotopically enriched compound or standard or controlin 100 millimolar potassium phosphate (pH 7.4) is incubated at 37° C.for 20 min. After incubation, the reaction is stopped by the addition ofan appropriate solvent (e.g. acetonitrile, 20% trichloroacetic acid, 94%acetonitrile/6% glacial acetic acid, 70% perchloric acid, 94%acetonitrile/6% glacial acetic acid) and centrifuged (10,000 g) for 3minutes. The supernatant is analyzed by HPLC/MS/MS.

Cytochrome P₄₅₀ Standard CYP1A2 Phenacetin CYP2A6 Coumarin CYP2B6[¹³C]—(S)-mephenytoin CYP2C8 Paclitaxel CYP2C9 Diclofenac CYP2C19[¹³C]—(S)-mephenytoin CYP2D6 (+/−)-Bufuralol CYP2E1 Chlorzoxazone CYP3A4Testosterone CYP4A [¹³C]-Lauric acid

Example 23 Pentobarbital-induced Sleep Test in Mice

Male Swiss mice (20-25 g) are randomly divided into groups of 10 andhoused in a vivarium with 12 hour light-dark cycle at 24±1° C. The testcompounds are dissolved in dimethylsulfoxide as stock solutions of 50mg/mL. Each group is i.p. injected with the test compounds 30 minutesbefore intravenous administration of pentobarbital sodium (25 mg/kg).The control group is treated i.p. with dimethylsulfoxide alone todetermine the duration of hypnosis. Sleep time in test animals andcontrol animals is determined by measuring the difference between thetime of loss and recovery of the righting reflex.

1. A compound having a structural formula selected from the groupconsisting of:

or a pharmaceutically acceptable salt thereof; wherein each positiondesignated as D has deuterium enrichment of at least 1%.
 2. The compoundof claim 1 wherein each position designated as D has deuteriumenrichment of at least 10%.
 3. The compound of claim 1 wherein eachposition designated as D has deuterium enrichment of at least 20%. 4.The compound of claim 1 wherein each position designated as D hasdeuterium enrichment of at least 50%.
 5. The compound of claim 1 whereineach position designated as D has deuterium enrichment of at least 70%.6. The compound of claim 1 wherein each position designated as D hasdeuterium enrichment of at least 80%.
 7. The compound of claim 1 whereineach position designated as D has deuterium enrichment of at least 90%.8. The compound of claim 1 wherein each position designated as D hasdeuterium enrichment of at least 95%.
 9. A pharmaceutical compositioncomprising a therapeutically effective amount of a compound according toclaim 1 together with a pharmaceutically acceptable carrier orexcipient.
 10. The pharmaceutical composition of claim 9, wherein saidcomposition is suitable for oral, parenteral, or intravenous infusionadministration.
 11. The pharmaceutical composition of claim 10, whereinsaid oral administration comprises administering a tablet or a capsule.12. The pharmaceutical composition of claim 10, wherein said compound ofclaim 1 is administered in a dose of about 0.1 milligram to about 100milligram total daily.
 13. A compound as recited in claim 1, having thestructural formula:

wherein each position designated as D has deuterium enrichment of atleast 1%.
 14. A compound as recited in claim 1, having the structuralformula:

wherein each position designated as D has deuterium enrichment of atleast 1%.
 15. A compound as recited in claim 1, having the structuralformula:

wherein each position designated as D has deuterium enrichment of atleast 1%.
 16. A compound as recited in claim 1, having the structuralformula:

wherein each position designated as D has deuterium enrichment of atleast 1%.
 17. A compound as recited in claim 1, having the structuralformula:

wherein each position designated as D has deuterium enrichment of atleast 1%.